No full-text available
To read the full-text of this research,
you can request a copy directly from the authors.
The Clinical Significance Of Freezing While Turning in Parkinson’s Disease
Abstract
Freezing of gait (FoG) in people with Parkinson's disease (PD) is an environmentally sensitive, intermittent problem that occurs most often during turning. FoG is difficult for clinicians to evaluate and treat because it can be difficult to elicit during a clinical visit. Here, we aimed to develop a clinically valid objective measure of freezing severity during a 2-minute 360 degrees turning-in-place. Twenty-eight subjects with PD (16 freezers, FoG+, and 12 nonfreezers, FoG-) in the "off" state and 14 healthy control subjects were tested. Subjects wore 3 inertial sensors (one on each shin and one on the waist) while 1) turning in place for 2 minutes (alternating 360 degrees to the right with 360 degrees to the left) and 2) performing an Instrumented 7m Timed Up and Go test (ITUG). Performance was videotaped, and clinical severity of FoG was independently rated by two movement disorders specialists (co-authors). Turning in place consistently resulted in FoG (13 out of 16 subjects with PD) while FoG was clinically observed in only 2 subjects with PD during the ITUG test. The Freezing Ratio during the turning test was significantly correlated with the clinical ratings (ρ=0.7, p=0.003) and with score on the new freezing of gait questionnaire (ρ=0.5, p=0.03). After correcting for symptom severity (UPDRS-III), out of the 4 objective measures of the turning test (total number of turns, average turn peak speed and average turn smoothness), only the Freezing Ratio was significantly different across groups (p=0.04). Freezing can be well quantified with body-worn inertial sensors during a 2-minute turning-in-place protocol.
... In the past, we have used the Freezing Ratio, the square of the total power in the 3-8 Hz band, divided by the square of the total power in the 0.5-3 Hz band, from the antero-posterior accelerations of the lower limbs during turning in-place as a measure of FoG [11,12]. This Freezing Ratio during 360° turns was significantly associated with: (1) FoG severity assessed by two expert movement disorders neurologists on a scale from 0 (absent) to 4 (needing assistance) and (2) FoG perception assessed by the FoG questionnaire [12]. ...
... In the past, we have used the Freezing Ratio, the square of the total power in the 3-8 Hz band, divided by the square of the total power in the 0.5-3 Hz band, from the antero-posterior accelerations of the lower limbs during turning in-place as a measure of FoG [11,12]. This Freezing Ratio during 360° turns was significantly associated with: (1) FoG severity assessed by two expert movement disorders neurologists on a scale from 0 (absent) to 4 (needing assistance) and (2) FoG perception assessed by the FoG questionnaire [12]. However, other groups have noted that the Freezing Ratio is not sensitive to akinetic periods of FoG [13]. ...
... Currently, clinical care and research divides PD subjects into freezers and non-freezers. However, the Freezing Ratio for people with PD not reporting FoG was in between the values of the healthy controls and the people reporting FoG [12]. We hypothesize that FoG is not one of two, clearly distinct states, present or absent, but rather FoG consists of a continuum of severity across the clinical course of PD. ...
Over the course of the disease, freezing of gait (FoG) will gradually impact over 80% of people with Parkinson’s disease (PD). Clinical decision-making and research design are often based on classification of patients as ‘freezers’ or ‘non-freezers’. We derived an objective measure of FoG severity from inertial sensors on the legs to examine the continuum of FoG from absent to possible and severe in people with PD and in healthy controls. One hundred and forty-seven people with PD (Off-medication) and 83 healthy control subjects turned 360° in-place for 1 minute while wearing three wearable sensors used to calculate a novel Freezing Index. People with PD were classified as: ‘definite freezers’, new FoG questionnaire (NFOGQ) score > 0 and clinically observed FoG; ‘non-freezers’, NFOGQ = 0 and no clinically observed FoG; and ‘possible freezers’, either NFOGQ > 0 but no FoG observed or NFOGQ = 0 but FoG observed. Linear mixed models were used to investigate differences in participant characteristics among groups. The Freezing Index significantly increased from healthy controls to non-freezers to possible freezers and to definite freezers and showed, in average, excellent test–retest reliability (ICC = 0.89). Unlike the Freezing Index, sway, gait and turning impairments were similar across non-freezers, possible and definite freezers. The Freezing Index was significantly related to NFOG-Q, disease duration, severity, balance confidence, and the SCOPA-Cog (p < 0.01). An increase in the Freezing Index, objectively assessed with wearable sensors during a turning- in-place test, may help identify prodromal FoG in people with PD prior to clinically-observable or patient-perceived freezing. Future work should follow objective measures of FoG longitudinally.
... Freezing of gait (FOG) is one of the most disabling features of Parkinson's disease (PD) [1]. FOG motor disorder represents an intermittent failure to initiate or maintain locomotion [2]. FOG was defined in 2010, as a "brief episodic absence or marked reduction in stride progression despite the intention to walk" [3]. ...
... The volunteers were able to walk independently for 10 m and reported experiencing FOG in the prior month. FOG severity was rated using the New Freezing of Gait Questionnaire (new FOG-Q) [1,2,5,27,31,32]. All the participants had a FOG history with different severity and frequency [20]. ...
... All subjects were assessed first in the morning in the OFF-medication state, which is at least 12 h since the last intake of dopaminergic medication, then after data collection, they took their first dose of dopaminergic medication of the day and the experiment was repeated after 40-50 min, at the ON-medication stage [4,13,27,32]. Clinical data to rate severity of PD, as the MDS-UPDRS and the Hoehn and Yahr Scale, were collected during the OFF and ON states [2,4,32]. ...
Freezing of gait (FOG), one of the most disabling features of Parkinson’s disease (PD), is a brief episodic absence or marked reduction in stride progression despite the intention to walk. Progressively more people who experience FOG restrict their walking and reduce their level of physical activity. The purpose of this study is to develop and validate a physical mobility task that induces freezing of gait in a controlled environment, employing known triggers of FOG episodes according to the literature. To validate the physical mobility tasks, we recruited 10 volunteers that suffered PD-associated freezing (60.6 ± 7.29 years-old) with new FOG-Q ranging from 12 to 26. The validation of the proposed method was carried out using inertial sensors and video recordings. All subjects were assessed during the OFF and ON medication states. The total number of FOG occurrences during data collection was 144. The proposed tasks were able to trigger 120 FOG episodes, while the TUG test caused 24. The Inertial Measurement Unit (IMU) with accelerometer and gyroscope could not only detect FOG episodes but also allowed us to visualize the three types of FOG: akinesia, festination and trembling in place.
... Our current work fills the gap in two critical points. First, none of these studies included data during the turning phase; this is an important limitation as studies have shown that FoG events are very frequent during the turning phase in PD patients (Mancini et al., 2017). Second, given the variability of the patients' conditions (severity of the PD, level of medication), precise control of the clinical and medication status is necessary. ...
... The FoG-ratio was then calculated as the ratio between the square of the total power in the frequency band corresponding to freezing episodes (3-8 Hz) and the total power in the frequency band corresponding to locomotion (0.5-3 Hz). Thus, higher FoG-ratio scores indicate greater FoG severity (Mancini et al., 2017). Finally, Spearman correlation coefficient (one-tailed) was used to determine the correlation of subjective FoG measures (NFoG-Q score) with the total time of FoG during the turning task (s) and FoG-ratio. ...
... Our results demonstrated a significant correlation between subjective (NFoG-Q) and objective (FoG-ratio, and total time of FoG during turning task) FoG measures, as observed previously (Mancini et al., 2017). This result is interesting for two reasons. ...
... Stepping in place (Nantel et al., 2011) Walking course (Ziegler et al., 2010) Virtual reality walking course (Shine et al., 2013a) Set walking course or task standardises FOG triggers across subjects FOG provoking tasks (e.g., dual tasking, turning, doorway walking, approaching target) can be incorporated to more reliably elicit FOG in laboratory settings Virtual reality walking allows manipulation of the walking environment (e.g., increase threat and anxiety) to assess their impacts on FOG (Ehgoetz Martens et al., 2015) Could be less sensitive to FOG as gait becomes more goal directed and less automatic Subjects requiring gait aids or those likely to fall may not be safe to complete the tasks Visual scoring of FOG Video Live rater Facilitates quantification of FOG (e.g., FOG duration, number of episodes, % time frozen) Video data is easily shared between multiple raters Ability to adjust play-back speed and replay video to identify short FOG Less sensitive to FOG as gait becomes more goal directed Time-intensive processing by human raters Variability between clinicians' ratings across centres, more so in the live setting Algorithms for automatic video processing not yet at high accuracy Instrument-based freezing indices Accelerometer [Freezing Ratio (Mancini et al., 2017)] Pressure mat Electromyography Smart phone Combination Allows for faster processing speed if using automated algorithm Requires specialised and often bulky equipment, again limiting assessment in the home Body-worn sensors may interfere with normal gait ...
... Instruments such as accelerometers (Moore et al., 2008;Mancini et al., 2012Mancini et al., , 2017, force plates under the feet (Nantel et al., 2011), and lower limb surface electromyography (Nieuwboer et al., 2004) have all been used in the gait laboratory setting to quantify freezing along with a range of algorithms to produce an automated FOG detection mechanism. Previously, researchers have shown that body-worn inertial sensors can record a Freezing Ratio during a 2-min turning in place protocol that correlated well with clinical ratings of FOG (Mancini et al., 2017). ...
... Instruments such as accelerometers (Moore et al., 2008;Mancini et al., 2012Mancini et al., , 2017, force plates under the feet (Nantel et al., 2011), and lower limb surface electromyography (Nieuwboer et al., 2004) have all been used in the gait laboratory setting to quantify freezing along with a range of algorithms to produce an automated FOG detection mechanism. Previously, researchers have shown that body-worn inertial sensors can record a Freezing Ratio during a 2-min turning in place protocol that correlated well with clinical ratings of FOG (Mancini et al., 2017). However, these instrumented algorithms have not been widely validated for FOG assessment outside of their specific research purpose. ...
Freezing of gait (FOG) is a common and challenging clinical symptom in Parkinson’s disease. In this review, we summarise the recent insights into freezing of gait and highlight the strategies that should be considered to improve future treatment. There is a need to develop individualised and on-demand therapies, through improved detection and wearable technologies. Whilst there already exist a number of pharmacological (e.g., dopaminergic and beyond dopamine), non-pharmacological (physiotherapy and cueing, cognitive training, and non-invasive brain stimulation) and surgical approaches to freezing (i.e., dual-site deep brain stimulation, closed-loop programming), an integrated collaborative approach to future research in this complex area will be necessary to systematically investigate new therapeutic avenues. A review of the literature suggests standardising how gait freezing is measured, enriching patient cohorts for preventative studies, and harnessing the power of existing data, could help lead to more effective treatments for freezing of gait and offer relief to many patients.
... Freezing of gait (FOG), often defined as a feeling of one's feet being "glued" to the floor [1,2], is a debilitating phenomenon in Parkinson's disease (PD) that negatively impacts quality of life and can lead to falls, serious injury, or even death [3][4][5][6]. FOG is a challenging phenomenon to objectively measure in the clinic and laboratory [7], but several tasks, such as 360-degree turning in place [8], the turning and barrier course (TBC) [9], and stepping in place (SIP) [10], have been developed to safely and reliably elicit FOG. ...
... Arrhythmicity was calculated as the average stride time CV of the previous three stride times of the left and right leg. Freeze index was defined as the power in the freezing band (3)(4)(5)(6)(7)(8) divided by the power in the gait band (0.5-3 Hz) [40]. Analysis of these gait parameters was performed in MATLAB (version 9.8, The MathWorks Inc., Natick, MA, USA). ...
... Logistic regression models based on kinematic data measured from wearable IMUs detected FOG during SIP on a step-by-step basis. The general model achieved an AUC value of 0.81, accuracy of 0.84, sensitivity of 0.86, and specificity of 0.81, which are similar to other IMU-based FOG detection algorithms [8,9,41]. ...
Freezing of gait (FOG), a debilitating symptom of Parkinson’s disease (PD), can be safely studied using the stepping in place (SIP) task. However, clinical, visual identification of FOG during SIP is subjective and time consuming, and automatic FOG detection during SIP currently requires measuring the center of pressure on dual force plates. This study examines whether FOG elicited during SIP in 10 individuals with PD could be reliably detected using kinematic data measured from wearable inertial measurement unit sensors (IMUs). A general, logistic regression model (area under the curve = 0.81) determined that three gait parameters together were overall the most robust predictors of FOG during SIP: arrhythmicity, swing time coefficient of variation, and swing angular range. Participant-specific models revealed varying sets of gait parameters that best predicted FOG for each participant, highlighting variable FOG behaviors, and demonstrated equal or better performance for 6 out of the 10 participants, suggesting the opportunity for model personalization. The results of this study demonstrated that gait parameters measured from wearable IMUs reliably detected FOG during SIP, and the general and participant-specific gait parameters allude to variable FOG behaviors that could inform more personalized approaches for treatment of FOG and gait impairment in PD.
... Turning is also the most consistent trigger of FOG, especially when full turns (360 • ) are performed at fast speed [5]. The close link between FOG and turning is also testified by the fact that the ratio between power in the freezing band (3-8 Hertz (Hz)) and gait band (0.5-3 Hz) during repeated 360 • turning was shown to be a valid measure of freezing severity [6]. FOG-episodes during turning were preceded by a less medial position of the CoM and a reduction of step width [7]. ...
... Participants performed alternating 360 • right and left turns on the spot for one minute at self-preferred speed while wearing wireless synchronized inertial sensors (Opals by APDM, Inc) on the shins and sacrum [6]. Average and peak angular velocity within each turn were calculated and averaged over turns to give the mean and peak turning speed. ...
... Average and peak angular velocity within each turn were calculated and averaged over turns to give the mean and peak turning speed. Turning fluidity was characterized through turn jerkiness, calculated as the integral of the squared time derivative of the accelerometer signal in the mediolateral direction [6]. The FOG-ratio during turning was calculated from the accelerometer signals from the shins in the anteroposterior direction as per prior work [6]. ...
Background:
People with Parkinson's disease and freezing of gait (FOG; freezers) suffer from pronounced postural instability. However, the relationship between these phenomena remains unclear and has mostly been tested in paradigms requiring step generation.
Objective:
To determine if freezing-related dynamic balance deficits are present during a task without stepping and determine the influence of dopaminergic medication on dynamic balance control.
Methods:
Twenty-two freezers, 16 non-freezers, and 20 healthy age-matched controls performed mediolateral weight-shifts at increasing frequencies when following a visual target projected on a screen (MELBA task). The amplitude and phase shift differences between center of mass and target motion were measured. Balance scores (Mini-BESTest), 360° turning speed and the freezing ratio were also measured. Subjects with Parkinson's disease were tested ON and partial OFF (overnight withdrawal) dopaminergic medication.
Results:
Freezers had comparable turning speed and balance scores to non-freezers and took more levodopa. Freezers produced hypokinetic weight-shift amplitudes throughout the MELBA task compared to non-freezers (p = 0.002), which were already present at task onset (p < 0.001). Freezers also displayed an earlier weight-shift breakdown than controls when OFF-medication (p = 0.008). Medication improved mediolateral weight-shifting in freezers and non-freezers. Freezers decreased their freezing ratio in response to medication.
Conclusion:
Hypokinetic weight-shifting proved a marked postural control deficit in freezers, while balance scores and turning speed were similar to non-freezers. Both weight-shift amplitudes and the freezing ratio were responsive to medication in freezers, suggesting axial motor vigor is levodopa-responsive. Future work needs to test whether weight-shifting and freezing severity can be further ameliorated through training.
... 10 This requires video annotations, 10 which is unfeasible for routine clinical practice. From as early as 1993, clinician-rated FOG severity outcomes have been publishedsome without validity and reliability investigated, 11,12 some with only reliability, [13][14][15] and some with both validity and reliability reported. [16][17][18][19] However, none have translated to routine clinical practice, with clinicians expressing reasons of perceived impracticality and lack of usefulness. ...
... 20 It allows walking aid use, does not involve standing up from a chair, and may be more successful in triggering FOG given the larger turning angle and smaller width of the narrow-space. 14,[20][21][22]39,40 Compared to the commonly-used Timed Up and Go, 34 the FOG Severity Tool had 6.2 times the odds of eliciting FOG. 21 With the aim of providing a quick and easy-to-use clinical measure, this study is the author/funder, who has granted medRxiv a license to display the preprint in (which was not certified by peer review) preprint ...
Objectives
Existing objective assessments for freezing of gait (FOG) severity may be unwieldy for routine clinical practice. To provide an easy-to-use clinical measure, this cross-sectional study explored if time to complete the recently-validated FOG Severity Tool (or its components) could be used to reflect FOG severity.
Methods
People with Parkinson’s disease who could independently ambulate eight-metres, understand instructions, and without co-morbidities severely affecting gait were consecutively recruited from outpatient clinics. Participants were assessed with the FOG Severity Tool in a test-retest design, with time taken for each component recorded using a stopwatch during video-analysis. Validity of total FOG Severity Tool time, time taken to complete its turning and narrow-space components (i.e., Time To Navigate, TTN), and an adjusted-TTN were examined through correlations with the FOG Questionnaire, percentage of time spent with FOG, and FOG Severity Tool-Revised score. To facilitate clinical interpretation, TTN cutoff was determined using scatterplot smoothing (LOESS) regression whilst minimal important change (MIC) was calculated using predictive modelling.
Results
Thirty-five participants were included [82.9%(n=29)male; Median(IQR): age – 73.0(11.0)years; disease duration – 4.0(4.5)years]. The FOG Severity Tool time, TTN, and adjusted-TTN similarly demonstrated moderate correlations with the FOG Questionnaire and percentage-FOG, and very-high correlations with FOG Severity Tool-Revised. TTN was nonlinearly related to FOG severity such that a positive relationship was observed in the first 300-seconds, beyond which the association plateaued. MIC for TTN was 15.4-seconds reduction in timing (95%CI 3.2 to 28.7).
Conclusions
The TTN is a feasible, interpretable, and valid test of FOG severity, demonstrating strong convergent validity with the FOG Severity Tool-Revised. In busy clinical settings, TTN provides a viable alternative when use of existing objective FOG measures is (often) unfeasible.
Impact statement
Busy clinicians need easy-to-use measures. In under 300-seconds, TTN test offers this for FOG severity, with a 15.4-seconds decrease in TTN time considered minimal improvement.
... Different from straight-line walking, turning involves a series of complex motor tasks, such as forward motion deceleration, trunk rotation, and stepping redirection [2,3]. Thus, turning is considered as a more challenging motor task than straight-line walking, especially for those with walking impairments [4]. More importantly, turning is associated with an increased risk of falls and injuries [5]. ...
... Gait & Posture 101 (2023)[1][2][3][4][5][6][7] ...
Background:
Turning gait is considered as a challenging motor task. However, only few existing studies reported turning biomechanics from the aspect of foot plantar pressure.
Research question:
This study aimed to investigate turning biomechanics by studying foot plantar pressure characteristics METHODS: Twelve young male participants were involved in this experimental study. They were instructed to perform turning tasks with different turning angles (i.e., 30°, 60°, and 90°). Foot plantar pressure was quantified by the force time integral (FTI) underneath seven plantar sub-areas. Analysis was carried out for different turning strategies (spin turns versus step turns), separately.
Results:
The results showed that for small-angle spin turns, plantar pressure patterns changed at the early stage of the approaching step, suggesting a preparatory action for the increased lower limb range of motion in the transverse plane during turning; for step turns, an imbalance weight bearing mechanism was adopted when making large-angle turns to compensate for the centripetal force during turning.
Significance:
The findings provide improved knowledge about turning biomechanics. They have practical implications for motion planning of lower-limb assistive devices for those with difficulties in turning.
... We calculated the percentage change in the FoG Index during turning in place using cues (open and closedloop independently) relative to baseline. The FoG Index is a validated measure of FoG (Mancini et al., 2017) in the laboratory and reflects freezing severity. It is calculated as the power spectral density ratio between high (3-8 Hz) and low (0-3 Hz) frequencies of anteroposterior shin accelerations (Mancini et al., 2017). ...
... The FoG Index is a validated measure of FoG (Mancini et al., 2017) in the laboratory and reflects freezing severity. It is calculated as the power spectral density ratio between high (3-8 Hz) and low (0-3 Hz) frequencies of anteroposterior shin accelerations (Mancini et al., 2017). ...
We previously showed that both open-loop (beat of a metronome) and closed-loop (phase-dependent tactile feedback) cueing may be similarly effective in reducing Freezing of Gait (FoG), assessed with a quantitative FoG Index, while turning in place in the laboratory in a group of people with Parkinson’s disease (PD). Despite the similar changes on the FoG Index, it is not known whether both cueing responses require attentional control, which would explain FoG Index improvement. The mechanisms underlying cueing responses are poorly understood. Here, we tested the hypothesis that the salience network would predict responsiveness (i.e., FoG Index improvement) to open-loop and closed-loop cueing in people with and without FoG of PD, as salience network contributes to tasks requiring attention to external stimuli in healthy adults. Thirteen people with PD with high-quality imaging data were analyzed to characterize relationships between resting-state MRI functional connectivity and responses to cues. The interaction of the salience network and retrosplenial-temporal networks was the best predictor of responsiveness to open-loop cueing, presenting the largest effect size (d=1.16). The interaction between the salience network and subcortical as well as cingulo-parietal and subcortical networks were the strongest predictors of responsiveness to closed-loop cueing, presenting the largest effect sizes (d=1.06 and d=0.84, respectively). Salience network activity was a common predictor of responsiveness to both cueing, which suggests that auditory and proprioceptive stimuli during turning may require some level of cognitive and insular activity, anchored within the salience network, which explain FoG Index improvements in people with PD.
... Mancini et al. [32] reported that as FOG severity increases in freezers, the ability to coordinate natural movement and normal gait patterns might be impaired along with increased FOG rate and asymmetric steps during turning. These results suggest that FOG symptoms are related to the degeneration of the spinal cord pattern generator rather than the frontal cortex, including the motor cortex and supplementary motor area [32]. ...
... Mancini et al. [32] reported that as FOG severity increases in freezers, the ability to coordinate natural movement and normal gait patterns might be impaired along with increased FOG rate and asymmetric steps during turning. These results suggest that FOG symptoms are related to the degeneration of the spinal cord pattern generator rather than the frontal cortex, including the motor cortex and supplementary motor area [32]. Therefore, the results of our study on the association between NFOGQ score and turning characteristics of the direction according to the influence of unilateral motor symptoms within freezers may be helpful for early diagnosis and prediction studies according to the severity of FOG. ...
For people with Parkinson's disease (PD) with freezing of gait (FOG) (freezers), symptoms mainly exhibit as unilateral motor impairments that may cause difficulty during postural transitions such as turning during daily activities. We investigated the turning characteristics that distinguished freezers among people with PD and analyzed the association between the New Freezing of Gait Questionnaire (NFOGQ) scores and the gait characteristics according to the turning direction for the affected limbs of freezers. The study recruited 57 people with PD (27 freezers, 30 non-freezers). All experiments measured the maximum 180° turning task with the "Off" medication state. Results revealed that the outer ankle range of motion in the direction of the inner step of the more affected limb (IMA) was identified to distinguish freezers and non-freezers (RN2 = 0.735). In addition, higher NFOGQ scores were associated with a more significant anteroposterior root mean square distance of the center of mass in the IMA direction and a greater inner stance phase in the outer step of the more affected limb (OMA) direction; explanatory power was 50.1%. Assessing the maximum speed and turning direction is useful for evaluating the differences in turning characteristics between freezers and non-freezers, which can help define freezers more accurately.
... FOG-severity was evaluated as a secondary outcome in the group of freezers only by calculating: (1) the FOG-score during walking in a FOG-provoking protocol, 28 (2) the percentage of time frozen, 26 and (3) the FOG-ratio (mediolateral) 29 during the 360 turning test. ...
... However, turning is deemed a complex task requiring visual guidance, extensive sensory integration, and head-pelvis dissociation. 29 Because turning on the spot does not capture a shift from straight-line walking to asymmetrical gait, it may have been too dissimilar as a near or far marker of transfer. ...
Background: Gait deficits in people with Parkinson's disease (PD) are triggered by circumstances requiring gait adaptation. The effects of gait adaptation training on a split-belt treadmill (SBT) are unknown in PD.
Objective: We investigated the effects of repeated SBT versus tied-belt treadmill (TBT) training on retention and automaticity of gait adaptation and its transfer to over-ground walking and turning.
Methods: We recruited 52 individuals with PD, of whom 22 were freezers, in a multi-center randomized single-blind controlled study. Training consisted of 4 weeks of supervised treadmill training delivered three times per week. Tests were conducted pre- and post-training and at 4-weeks follow-up. Turning (primary outcome) and gait were assessed over-ground and during a gait adaptation protocol on the treadmill. All tasks were performed with and without a cognitive task.
Results: We found that SBT-training improved gait adaptation with moderate to large effects sizes (P < 0.02) compared to TBT, effects that were sustained at follow-up and during dual tasking. However, better gait adaptation did not transfer to over-ground turning speed. In both SBT- and TBT-arms, over-ground walking and Movement Disorder Society-Unified Parkinson's Disease Rating Scale III (MDS-UPDRS-III scores were improved, the latter of which reached clinically meaningful effects in the SBT-group only. No impact was found on freezing of gait.
Conclusion: People with PD are able to learn and retain the ability to overcome asymmetric gait-speed perturbations on a treadmill remarkably well, but seem unable to generalize these skills to asymmetric gait off-treadmill. Future study is warranted into gait adaptation training to boost the transfer of complex walking skills.
... While encouraging, the observations above are limited to forward stepping. However, FOG often occurs during turning, where weight-shifting is more complex and risk of falling is higher [14,15]. We therefore aimed to explore the efficacy of using a weight-shifting strategy to promote successful recovery following FOG during turning. ...
... This expands findings by Maslivec et al. [13] who showed the effectiveness of similar internally generated weight-shift strategies during forward stepping tasks. Turning -a known trigger of freezing [14,15] -is a more complex task due to the added complexities of co-ordinating the position of the centre of mass over the changing base of support while simultaneously rotating body segments. Our results suggest that the simple cha-cha weight-shifting cue can enhance turning without compromising safety, neither during the laboratory-based assessment nor during subsequent self-reported use in daily life. ...
Freezing of gait (FOG) can severely compromise daily functioning in people with Parkinson’s disease. Inability to initiate a step from FOG is likely underpinned, at least in part, by a deficient preparatory weight-shift. Conscious attempts to weight-shift in preparation to step can improve success of initiating forward steps following FOG. However, FOG often occurs during turning, where weight-shifting is more complex and risk of falling is higher. We explored the effectiveness of a dance-based (‘cha-cha’) weight-shifting strategy to re-initiate stepping following FOG during turning. Results suggest that this simple movement strategy can enhance turning steps following FOG, without compromising safety.
... We also collect sway in the medio-lateral plane as it is important for fall prevention, and we include perturbation tasks to challenge stability (see sections Dynamic Posturography on the Neurocom System and Selected Mini-BESTest Items, Two-Minute Walk Test, and a 360-Degrees Turning in Place With Opal Sensors below). Finally, our assessment captures straight walking and turning (see section Selected Mini-BESTest Items, Two-Minute Walk Test, and a 360-Degrees Turning in Place With Opal Sensors below) for overall clinical relevance, and because a subset of patients with PSP have freezing of gait. Figure 1 shows our comprehensive balance assessment protocol for PSP: the Sensory Organization Test (SOT) and Motor Control Test (MCT) with forward platform translation and toes-up perturbations on a Neurocom Balance Manager system, anticipatory postural adjustments, reactive postural control and sensory orientation aspects of the mini-BESTest (17), a two-minute walk test (23,24), and a 360-degree turning in place task (25). The mini-BESTest, two-minute walk, and 360degree turning task are all performed while wearing six Opal inertial measurement sensors (APDM Wearable Technologies, Portland, OR) (26). ...
... Both average and variability are reported. For the separate instrumented 360 degrees turning in place task, subjects are instructed to turn in place for a total of 1 min, 360 degrees to the right, then 360 degrees to the left (and so on) at a comfortable speed (25). This turning protocol elicits potential freezing of gait in a controlled manner. ...
Many studies have examined aspects of balance in progressive supranuclear palsy (PSP), but guidance on the feasibility of standardized objective balance assessments and balance scales in PSP is lacking. Balance tests commonly used in Parkinson's disease often cannot be easily administered or translated to PSP. Here we briefly review methodology in prior studies of balance in PSP; then we focus on feasibility by presenting our experience with objective balance assessment in PSP-Richardson syndrome and PSP-parkinsonism during a crossover rTMS intervention trial. We highlight lessons learned, safety considerations, and future approaches for objective balance assessment in PSP.
... Only Fietzek et al. 41 and Schlenstedt et al. 55 blinded the assessors to group allocation. Two recent studies 43,48 captured objective FOG severity using a FOG-ratio as derived from inertial measurement units during the performance of a turning on the spot task 71 . To date, only one study assessed FOG severity as the percentage of time spent with FOG as measured objectively from video recordings of standardized walking tasks and rated by independent and blinded assessors 50 . ...
... Software to annotate the video recordings for FOG can be downloaded for free from morangilat.com 88 . The standardized protocol should consist of a substantial number of FOG-provoking tasks, such as turning on the spot 69,71,113 . The percentage time frozen can be rated by independent investigators who are kept blinded to group allocation 41,50,55 . ...
Freezing of gait (FOG) in Parkinson’s disease (PD) causes severe patient burden despite pharmacological management. Exercise and training are therefore advocated as important adjunct therapies. In this meta-analysis, we assess the existing evidence for such interventions to reduce FOG, and further examine which type of training helps the restoration of gait function in particular. The primary meta-analysis across 41 studies and 1838 patients revealed a favorable moderate effect size (ES = −0.37) of various training modalities for reducing subjective FOG-severity ( p < 0.00001), though several interventions were not directly aimed at FOG and some included non-freezers. However, exercise and training also proved beneficial in a secondary analysis on freezers only (ES = −0.32, p = 0.007). We further revealed that dedicated training aimed at reducing FOG episodes (ES = −0.24) or ameliorating the underlying correlates of FOG (ES = −0.40) was moderately effective ( p < 0.01), while generic exercises were not (ES = −0.14, p = 0.12). Relevantly, no retention effects were seen after cessation of training (ES = −0.08, p = 0.36). This review thereby supports the implementation of targeted training as a treatment for FOG with the need for long-term engagement.
... More specifically, Moore et al. [16] found that FoG events are not described by purely stochastic events, but are indeed well defined in the low frequency band (3)(4)(5)(6)(7)(8) and proposed an index to objectively identify FoG events offline. Building on this finding, algorithms manipulating acceleration signals gathered from shinmounted sensors have been introduced [17,18] and applied to study the occurrence of FoG while turning [19]. A further development of this approach called for the use of both accelerometer and gyroscope signals collected from sensors mounted on the lateral aspect of tibia and segmented on a gait cycle basis. ...
... Being part of a larger project, the tasks listed in Table 2 were needed to simulate daily activities with the aim of triggering specific disease symptoms, with particular attention to FoG. Among these tasks, the 2 Minute Walking Test (2MWT), the 360 • turn test, and Timed Up and Go (TUG) were included as the benchmark for FoG triggering and evaluation [19,29,30]. The FoG detection algorithm was then applied to those tasks including walking: 3, 4b-c-d-e, 5 in Table 2. ...
Freezing of Gait (FoG) is a common symptom in Parkinson’s Disease (PD) occurring with significant variability and severity and is associated with increased risk of falls. FoG detection in everyday life is not trivial, particularly in patients manifesting the symptom only in specific conditions. Various wearable devices have been proposed to detect PD symptoms, primarily based on inertial sensors. We here report the results of the validation of a novel system based on a pair of pressure insoles equipped with a 3D accelerometer to detect FoG episodes. Twenty PD patients attended a motor assessment protocol organized into eight multiple video recorded sessions, both in clinical and ecological settings and both in the ON and OFF state. We compared the FoG episodes detected using the processed data gathered from the insoles with those tagged by a clinician on video recordings. The algorithm correctly detected 90% of the episodes. The false positive rate was 6% and the false negative rate 4%. The algorithm reliably detects freezing of gait in clinical settings while performing ecological tasks. This result is promising for freezing of gait detection in everyday life via wearable instrumented insoles that can be integrated into a more complex system for comprehensive motor symptom monitoring in PD.
... We used objective and continuous measures to assess severity of FoG as described previously (Mancini et al., 2017). Briefly, a FoG ratio was calculated from acceleration of the shins (measured via inertial sensors, Opals by APDM) during a 1-minute turning task in which subjects made alternating 360°turns as fast as safely possible (Figure 1). ...
... Higher freezing ratios indicate higher severity of FoG. FoG ratio has been shown to correlate well with FoG severity as measured by a video review of turning in place (Mancini et al., 2017). ...
Objective
Freezing of gait (FoG) in Parkinson’s disease (PD) has been associated with response inhibition. However, the relationship between response inhibition, neural dysfunction, and PD remains unclear. We assessed response inhibition and microstructural integrity of brain regions involved in response inhibition [right hemisphere inferior frontal cortex (IFC), bilateral pre-supplementary motor areas (preSMA), and subthalamic nuclei (STN)] in PD subjects with and without FoG and elderly controls.
Method
Twenty-one people with PD and FoG (PD-FoG), 18 without FoG (PD-noFoG), and 19 age-matched controls (HC) completed a Stop-Signal Task (SST) and MRI scan. Probabilistic fiber tractography assessed structural integrity (fractional anisotropy, FA) among IFC, preSMA, and STN regions.
Results
Stop-signal performance did not differ between PD and HC, nor between PD-FoG and PD-noFoG. Differences in white matter integrity were observed across groups (.001 < p < .064), but were restricted to PD versus HC groups; no differences in FA were observed between PD-FoG and PD-noFoG ( p > .096). Interestingly, worse FoG was associated with higher (better) mean FA in the r-preSMA, ( β = .547, p = .015). Microstructural integrity of the r-IFC, r-preSMA, and r-STN tracts correlated with stop-signal performance in HC ( p ≤ .019), but not people with PD.
Conclusion
These results do not support inefficient response inhibition in PD-FoG. Those with PD exhibited white matter loss in the response inhibition network, but this was not associated with FoG, nor with response inhibition deficits, suggesting FoG-specific neural changes may occur outside the response inhibition network. As shown previously, white matter loss was associated with response inhibition in elderly controls, suggesting PD may disturb this relationship.
... Participants were selected based on the following inclusion criteria: (1) diagnosis of idiopathic PD confirmed by a movement disorders specialist by UK Parkinson's Disease Society Brain Bank diagnostic criteria; (2) FoG confirmed by answering affirmatively item 1 of the new freezing of gait questionnaire (NFoG-Q) (Nieuwboer et al., 2009) and/or if FoG was observed during the 2-minute turning task during ON medication status (Mancini et al., 2017); (3) Hoehn and Yahr stage range 2-4; (4) Mini-Mental State Examination score (MMSE) >23 (Folstein et al., 1983); (5) absence of orthopedic or neurological disorders other than PD that might affect performance in the experimental task. The exclusion criterion was a failure to participate in all training sessions or the pre-and post-tests. ...
Perturbation-based balance training (PBT) exposes individuals to a series of sudden upright balance perturbations to improve their reactive postural responses. In this study, we aimed to evaluate the effect of a short PBT program on body balance recovery following a perturbation in individuals with freezing of gait due to Parkinson's disease. Volunteers (mean age = 64 years, SD = 10.6) were pseudorandomly assigned either to a PBT (n = 9) or to a resistance training (RT, n = 10) group. PBT was implemented through balance perturbations varying in the kind, direction, side, and magnitude of support base displacements. Both groups exercised with progressive difficulty/load activities twice a week for four weeks. Specific gains and generalization to dual-tasking and faster-than-trained support base displacements were evaluated 24 h after the end of the training, and retention was evaluated after 30 days of no training. Results showed that, compared to RT, PBT led to more stable postural responses in the 30-day retention evaluation, as indicated by decreased CoP displacement, velocity, and time to direction reversal and reduced numbers of near-falls. We found no transfer either to a dual-task or to a higher perturbation velocity. In conclusion, a training program based on diverse unpredictable balance perturbations improved the stability of reactive postural responses to those perturbations suffered during the training, without generalization to more challenging tasks.
... To objectively assess FOG severity, PD patients are asked to perform brief and standardized FOG-provoking tasks in clinical centers. Common tasks include timed-up-and-go (TUG) (16), 180 or 360 degrees turning while walking (17), and 360-degree turning-in-place (360Turn) (18). The TUG is commonly used in clinical practice since the task includes typical everyday motor tasks such as standing, walking, turning, and sitting. ...
Background:
Freezing of gait (FOG) is an episodic and highly disabling symptom of Parkinson's Disease (PD). Traditionally, FOG assessment relies on time-consuming visual inspection of camera footage. Therefore, previous studies have proposed portable and automated solutions to annotate FOG. However, automated FOG assessment is challenging due to gait variability caused by medication effects and varying FOG-provoking tasks. Moreover, whether automated approaches can differentiate FOG from typical everyday movements, such as volitional stops, remains to be determined. To address these questions, we evaluated an automated FOG assessment model with deep learning (DL) based on inertial measurement units (IMUs). We assessed its performance trained on all standardized FOG-provoking tasks and medication states, as well as on specific tasks and medication states. Furthermore, we examined the effect of adding stopping periods on FOG detection performance.
Methods:
Twelve PD patients with self-reported FOG (mean age 69.33 +/- 6.28 years) completed a FOG-provoking protocol, including timed-up-and-go and 360-degree turning-in-place tasks in On/Off dopaminergic medication states with/without volitional stopping. IMUs were attached to the pelvis and both sides of the tibia and talus. A multi-stage temporal convolutional network was developed to detect FOG episodes. FOG severity was quantified by the percentage of time frozen (%TF) and the number of freezing episodes (#FOG). The agreement between the model-generated outcomes and the gold standard experts' video annotation was assessed by the intra-class correlation coefficient (ICC).
Results:
For FOG assessment in trials without stopping, the agreement of our model was strong (ICC(%TF) = 0.92 [0.68, 0.98]; ICC(#FOG) = 0.95 [0.72, 0.99]). Models trained on a specific FOG-provoking task could not generalize to unseen tasks, while models trained on a specific medication state could generalize to unseen states. For assessment in trials with stopping, the model trained on stopping trials made fewer false positives than the model trained without stopping (ICC(%TF) = 0.95 [0.73, 0.99]; ICC(#FOG) = 0.79 [0.46, 0.94]).
Conclusion:
A DL model trained on IMU signals allows valid FOG assessment in trials with/without stops containing different medication states and FOG-provoking tasks. These results are encouraging and enable future work investigating automated FOG assessment during everyday life.
... Among the 23 studies, it was found that step speed and length as well as the number of turns were decreased, and the Center of Pressure velocity, step time variability, Knutsson score were increased. Those results usually used to indicate poor motor performance (Mancini et al., 2017;Belluscio et al., 2019;Kahya et al., 2019;Caliandro et al., 2020). However, the cortical activation of PFC, PMC, SMC, and SMA was increased or decreased during different motor and balance task. ...
Background: Neurological disorders with dyskinesia would seriously affect older people’s daily activities, which is not only associated with the degeneration or injury of the musculoskeletal or the nervous system but also associated with complex linkage between them. This study aims to review the relationship between motor performance and cortical activity of typical older neurological disorder patients with dyskinesia during walking and balance tasks.
Methods: Scopus, PubMed, and Web of Science databases were searched. Articles that described gait or balance performance and cortical activity of older Parkinson’s disease (PD), multiple sclerosis, and stroke patients using functional near-infrared spectroscopy were screened by the reviewers. A total of 23 full-text articles were included for review, following an initial yield of 377 studies.
Results: Participants were mostly PD patients, the prefrontal cortex was the favorite region of interest, and walking was the most popular test motor task, interventional studies were four. Seven studies used statistical methods to interpret the relationship between motor performance and cortical activation. The motor performance and cortical activation were simultaneously affected under difficult walking and balance task conditions. The concurrent changes of motor performance and cortical activation in reviewed studies contained the same direction change and different direction change.
Conclusion: Most of the reviewed studies reported poor motor performance and increased cortical activation of PD, stroke and multiple sclerosis older patients. The external motor performance such as step speed were analyzed only. The design and results were not comprehensive and profound. More than 5 weeks walking training or physiotherapy can contribute to motor function promotion as well as cortices activation of PD and stroke patients. Thus, further study is needed for more statistical analysis on the relationship between motor performance and activation of the motor-related cortex. More different type and program sports training intervention studies are needed to perform.
... Third, FOG was defined by FOGQ, which is a selfreported questionnaire and mainly depends on patients' subjective recall. Although FOGQ has been widely used to assess the severity of FOG and has been considered a reliable screening tool for FOG patients [28], in future studies, we would apply a more objective and quantifiable method for FOG symptom monitoring, such as 2-min 360 degrees turning in place [51]. In addition, cognitive assessments of our study were conducted under the medication "ON" state in order to minimize the effect of motor symptoms on cognition. ...
Background: Freezing of gait (FOG) is a common disabling symptom in Parkinson’s disease (PD). Cognitive impairment may contribute to FOG. Nevertheless, their correlations remain controversial. We aimed to investigate cognitive differences between PD patients with and without FOG (nFOG), explore correlations between FOG severity and cognitive performance and assess cognitive heterogeneity within the FOG patients. Methods: Seventy-four PD patients (41 FOG, 33 nFOG) and 32 healthy controls (HCs) were included. Comprehensive neuropsychological assessments testing cognitive domains of global cognition, executive function/attention, working memory, and visuospatial function were performed. Cognitive performance was compared between groups using independent t-test and ANCOVA adjusting for age, sex, education, disease duration and motor symptoms. The k-means cluster analysis was used to explore cognitive heterogeneity within the FOG group. Correlation between FOG severity and cognition were analyzed using partial correlations. Results: FOG patients showed significantly poorer performance in global cognition (MoCA, p < 0.001), frontal lobe function (FAB, p = 0.015), attention and working memory (SDMT, p < 0.001) and executive function (SIE, p = 0.038) than nFOG patients. The FOG group was divided into two clusters using the cluster analysis, of which cluster 1 exhibited worse cognition, and with older age, lower improvement rate, higher FOGQ3 score, and higher proportion of levodopa-unresponsive FOG than cluster 2. Further, in the FOG group, cognition was significantly correlated with FOG severity in MoCA (r = −0.382, p = 0.021), Stroop-C (r = 0.362, p = 0.030) and SIE (r = 0.369, p = 0.027). Conclusions: This study demonstrated that the cognitive impairments of FOG were mainly reflected by global cognition, frontal lobe function, executive function, attention and working memory. There may be heterogeneity in the cognitive impairment of FOG patients. Additionally, executive function was significantly correlated with FOG severity.
... cognitive impairment as measured by the Montreal Cognitive Assessment (MoCA, total score <26) (Marinus et al., 2011), or disorders and dysfunctions that affected balance were excluded. The FoG status of PD participants was determined by item III of the Freezing of Gait Questionnaire (FOGQ), with a score of 0 indicating PD-nFoG and a score ≥1 denoting PD-FoG (Giladi et al., 2000;Mancini et al., 2017). For HCs, individuals were eligible if they were 50-80 years (to match those with PD) and were in good health. ...
Background
Freezing of gait (FoG) is a severely disabling symptom in Parkinson’s disease (PD). The cortical mechanisms underlying FoG during locomotion tasks have rarely been investigated.Objectives
We aimed to compare the cerebral haemodynamic response during FoG-prone locomotion tasks in patients with PD and FoG (PD-FoG), patients with PD but without FoG (PD-nFoG), and healthy controls (HCs).Methods
Twelve PD-FoG patients, 10 PD-nFoG patients, and 12 HCs were included in the study. Locomotion tasks included normal stepping, normal turning and fast turning ranked as three difficulty levels based on kinematic requirements and probability of provoking FoG. During each task, we used functional near-infrared spectroscopy to capture concentration changes of oxygenated haemoglobin (ΔHBO2) and deoxygenated haemoglobin (ΔHHB) that reflected cortical activation, and recorded task performance time. The cortical regions of interest (ROIs) were prefrontal cortex (PFC), supplementary motor area (SMA), premotor cortex (PMC), and sensorimotor cortex (SMC). Intra-cortical functional connectivity during each task was estimated based on correlation of ΔHBO2 between ROIs. Two-way multivariate ANOVA with task performance time as a covariate was conducted to investigate task and group effects on cerebral haemodynamic responses of ROIs. Z statistics of z-scored connectivity between ROIs were used to determine task and group effects on functional connectivity.ResultsPD-FoG patients spent a nearly significant longer time completing locomotion tasks than PD-nFoG patients. Compared with PD-nFoG patients, they showed weaker activation (less ΔHBO2) in the PFC and PMC. Compared with HCs, they had comparable ΔHBO2 in all ROIs but more negative ΔHHB in the SMC, whereas PD-nFoG showed SMA and PMC hyperactivity but more negative ΔHHB in the SMC. With increased task difficulty, ΔHBO2 increased in each ROI except in the PFC. Regarding functional connectivity during normal stepping, PD-FoG patients showed positive and strong PFC-PMC connectivity, in contrast to the negative PFC-PMC connectivity observed in HCs. They also had greater PFC-SMC connectivity than the other groups. However, they exhibited decreased SMA-SMC connectivity when task difficulty increased and had lower SMA-PMC connectivity than HCs during fast turning.Conclusion
Insufficient compensatory cortical activation and depletion of functional connectivity during complex locomotion in PD-FoG patients could be potential mechanisms underlying FoG.Clinical trial registrationChinese clinical trial registry (URL: http://www.chictr.org.cn, registration number: ChiCTR2100042813).
... These previous findings may explain the strong association of FOG-ratio with DTC on stride length, but not with DTC on gait speed that we found here. Additionally, FOG-ratio represents a measure of 'trembling of the knees' that is the FOG hallmark Mancini et al., 2017;S. T. Moore, MacDougall, & Ondo, 2008). ...
Individuals with Parkinson’s disease (PD) and freezing of gait (FOG) have difficulty initiating and maintaining a healthy gait pattern; however, the relationship among FOG severity, gait initiation, and gait automaticity, in addition to the neural substrate of this relationship has not been investigated. This study investigated the association among FOG severity during turning (FOG-ratio), gait initiation (anticipatory postural adjustment [APA]), and gait automaticity (dual-task cost [DTC]), and the neural substrates of these associations. Thirty-four individuals with FOG of PD were assessed in the ON-medication state. FOG-ratio during a turning test, gait automaticity using DTC on stride length and gait speed, and APA during an event-related functional magnetic resonance imaging protocol to assess brain activity from the regions of interest (e.g., dorsolateral prefrontal cortex [DLPFC] and mesencephalic locomotor region [MLR]) were assessed in separated days. Results showed that FOG-ratio, APA amplitude, and DTC on stride length are negatively associated among them (P < 0.05). APA amplitude and DTC on stride length explained 59% of the FOG-ratio variance (P < 0.05). Although the activity of the right DLPFC and right MLR explained 55% of the FOG-ratio variance (P < 0.05) and 30% of the DTC on stride length variance (P ≤ 0.05), only the activity of the right MLR explained 23% of the APA amplitude (P < 0.05). FOG severity during turning, APA amplitude, and stride length automaticity are associated among them and share a similar locomotor substrate, as the MLR activity was a common brain region in explaining the variance of these variables.
... Some PwPD develop freezing of gait over the course of their disease progression 17 . Along with other groups, we have shown that PwPD with freezing of gait have differences in disease and gait features outside of the actual episodes of gait freezing [18][19][20][21][22][23][24][25][26][27][28][29][30][31] . We therefore performed a subgroup analysis using the presence or absence of freezing to split groups and compare to differential results previously reported in these sub-phenotypes of PwPD. ...
Introduction: Gait, balance and cognitive impairment make travel cumbersome for People with
Parkinson’s disease (PwPD). About 75% of PwPD cared for at the University of Arkansas for
Medical Sciences’ Movement Disorders Clinic reside in medically underserved areas (MUAs).
Validated remote evaluations could help improve their access to care. Our goal was to explore
the feasibility of telemedicine research visits for evaluation of multi-modal function in PwPD in
a rural state.
Methods: In-home telemedicine research visits were performed in PwPD. Motor and non-motor
disease features were evaluated and quantified by trained personnel, digital survey instruments
for self-assessments, digital voice recordings, and scanned and digitized Archimedes spiral
drawings. Participants MUA residence was determined after evaluations were completed.
Results: Twenty of the fifty PwPD enrolled resided in MUAs. The groups were well matched for
disease duration, modified motor UPDRS, and Montreal Cognitive assessment scores but MUA
participants were younger. Ninety-two percent were satisfied with their visit and 61% were more
likely to participate in future telemedicine research. MUA participants travelled longer distances,
with higher travel costs, lower income and education level. While 50% of MUA participants
reported self-reliance for in-person visits, 85% reported self-reliance for the telemedicine visit.
We rated audio-video quality highly in approximately 60% of visits in both groups. There was
good correlation with prior in-person research assessments in a subset of participants.
Conclusions: In-home research visits for PwPD in medically underserved areas are feasible and
could help improve access to care and research participation in these traditionally
underrepresented populations.
Key words: telemedicine, health equity, rural health, ambulatory monitoring, Parkinson disease,
medically underserved area
... As outcome measures, we used the 24 objective measures that we found to be most sensitive in discriminating between people with PD and healthy controls. 24 The FoG ratio was calculated from the sensors on the shins according to methods described in Mancini et al. 29 Motor and cognitive dual task (DTC) were calculated as in our previous paper. 25 Specifically, when a dual task was added to walking, the dual cost (DC) was calculated as DC (%) = 100 × (dual-task measure-single-task measure)/single-task measure. ...
Background and Aim
Individuals with Parkinson’s disease (PD) with and without freezing of Gait (FoG) may respond differently to exercise interventions for several reasons, including disease duration. This study aimed to determine whether both people with and without FoG benefit from the Agility Boot Camp with Cognitive Challenges (ABC-C) program.
Methods
This secondary analysis of our ABC-C trial included 86 PD subjects: 44 without FoG (PD−FoG) and 42 with FoG (PD + FoG). We collected measures of standing sway balance, anticipatory postural adjustments, postural responses, and a 2-minute walk with and without a cognitive task. Two-way repeated analysis of variance, with disease duration as covariate, was used to investigate the effects of ABC-C program. Effect sizes were calculated using standardized response mean (SRM) for PD−FoG and PD + FoG, separately.
Results
The ABC-C program was effective in improving gait performance in both PD−FoG and PD + FoG, even after controlling for disease duration. Specifically, dual-task gait speed ( P < .0001), dual-cost stride length ( P = .012), and these single-task measures: arm range of motion ( P < .0001), toe-off angle ( P = .005), gait cycle duration variability ( P = .019), trunk coronal range of motion ( P = .042), and stance time ( P = .046) improved in both PD−FoG and PD + FoG. There was no interaction effect between time (before and after exercise) and group (PD−FoG/PD + FoG) in all 24 objective measures of balance and gait. Dual-task gait speed improved the most in PD + FoG (SRM = 1.01), whereas single-task arm range of motion improved the most in PD−FoG (SRM = 1.01).
Conclusion
The ABC-C program was similarly effective in improving gait (and not balance) performance in both PD−FoG and PD + FoG.
... This neuroimaging approach has been extensively used in studying the neural correlates of FoG in patients with PD as it permits the assessment of the whole brain without an experimental task. Rs-fMRI quantifies the functional connectivity between spatially disparate neural networks (intrinsic connectivity networks, ICN) by detecting fluctuations in spontaneous BOLD signals across the whole brain (Mancini et al., 2017). The parameters derived from rs-fMRI indicate a correlation (coupled) or an anti-correlation (anti-coupled) in the activity of the examined specific functional neural networks/ICNs (Biswal et al., 1995;Grayson and Fair, 2017). ...
Freezing of gait (FoG) is a paroxysmal and sporadic gait impairment that severely affects PD patients’ quality of life. This review summarizes current neuroimaging investigations that characterize the neural underpinnings of FoG in PD. The review presents and discusses the latest advances across multiple methodological domains that shed light on structural correlates, connectivity changes, and activation patterns associated with the different pathophysiological models of FoG in PD. Resting-state fMRI studies mainly report cortico-striatal decoupling and disruptions in connectivity along the dorsal stream of visuomotor processing, thus supporting the ‘interference’ and the ‘perceptual dysfunction’ models of FoG. Task-based MRI studies employing virtual reality and motor imagery paradigms reveal a disruption in functional connectivity between cortical and subcortical regions and an increased recruitment of parieto-occipital regions, thus corroborating the ‘interference’ and ‘perceptual dysfunction’ models of FoG. The main findings of fNIRS studies of actual gait primarily reveal increased recruitment of frontal areas during gait, supporting the ‘executive dysfunction’ model of FoG. Finally, we discuss how identifying the neural substrates of FoG may open new avenues to develop efficient treatment strategies.
... The new FOG-Q has recently been found to be unreliable and not responsive to small effect sizes [7]. Measures that rely on capturing a FOG episode in the laboratory (direct measures) [8][9][10][11][12] are limited by the inherent variability of each episode; therefore, a captured episode may not be representative of overall FOG severity. Furthermore, approaches to reliably trigger an episode have not been established. ...
Background
Freezing of gait (FOG) is notoriously difficult to quantify, which has led to the use of multiple markers as outcomes for clinical trials. The instrumented timed up and go (TUG) and the many parameters that can be derived from it are commonly used as objective markers of FOG severity in clinical trials; however, it is unknown if they represent actual FOG severity.
Objective
To determine the specificity and responsiveness of objective surrogate markers of FOG severity commonly utilized in FOG studies.
Methods
Study design: We compared the specificity and responsiveness of commonly used markers in FOG clinical trials. Markers compared included velocity, step/stride length, step/stride length variability, TUG, and turn duration. Data was collected in four conditions (ON and OFF dopaminergic drugs, with and without a dual task). Unified Parkinson’s Disease Rating Scale (UPDRS) was administered in the ON and OFF states.
Results
Thirty-three subjects were recruited (17 PD subjects without FOG (PD-control) and 16 subjects with PD and dopa-responsive FOG PD-FOG). The UPDRS motor scores were 24.9 for the PD-control group in the ON state, 24.8 for the FOG group in the ON state, and 42.4 for the FOG group in the OFF state. Significant mean differences between the ON and OFF conditions were observed with all surrogate markers (p < 0.01). However, only dual task turn duration and step variability showed trends toward significance when comparing PD-control and ON-FOG (p = 0.08). Test–retest reliability was high (ICC > 0.90) for all markers except standard deviations. Step length variability was the only marker to show an area under the ROC curve analysis > 0.70 comparing ON-FOG vs. PD-control.
Conclusions
Multiple candidate surrogate markers for FOG severity showed responsiveness to levodopa challenge; however, most were not specific for FOG severity.
... The SO section includes stabilometry tests on different surfaces (namely hard, soft and 30 • inclined) with both eyes-open (EO) and eyes-closed (EC) conditions and exploring both single and dualtask paradigms (DT). The DG section, instead, includes of Timed Up and Go (TUG) with and without dual-tasking to determine the effects of cognitive load on gait performance [48][49][50][51]. In the first three sections of the test, the maximum score is 6 and for the latter is 10, with a maximum total score of 28 points [47]. ...
The main objective of this study is to test the effect of thermal aquatic exercise on motor symptoms and quality of life in people with Parkinson’s Disease (PD). Fourteen participants with diagnosisofidiopathicPDcompletedthewholerehabilitationsessionandevaluationprotocol(Hoehn and Yahr in OFF state: 2–3; Mini Mental State Examination >24; stable pharmacological treatment in the 3 months prior participating in the study). Cognitive and motor status, functional abilities and qualityoflifewereassessedatbaselineandafteranintensiverehabilitationprograminthermalwater (12 sessions of 45 min in a 1.4 m depth pool at 32–36◦C). The Mini Balance Evaluation System Test (Mini-BESTest)andthePDQualityofLifeQuestionnaire(PDQ-39)wereconsideredasmainoutcomes. Secondary assessment measures evaluated motor symptoms and quality of life and psychological well-being. Participants kept good cognitive and functional status after treatment. Balance of all the participants significantly improved (Mini-BESTest: p < 0.01). The PDQ-39 significantly improved after rehabilitation (p = 0.038), with significance being driven by dimensions strongly related to motor status. Thermal aquatic exercise may represent a promising rehabilitation tool to prevent the impact of motor symptoms on daily-life activities of people with PD. PDQ-39 improvement foreshows good effects of the intervention on quality of life and psychological well-being.
... Dessa forma, vários estudos vêm sendo realizados, com intuito de revelar novos avanços na avaliação e tratamento do congelamento da marcha, devido ser um sintoma difícil para ser avaliado com precisão, por meio da observação, visto que os resultados obtidos acabam sendo subjetivos, apenas com base em relatos dos pacientes (MANCINI et al., 2017). Além disso, é um sintoma episódico e pode desaparecer durante a avaliação clínica devido a portador estar atento na sua marcha (BARTHEL et al., 2016). ...
... Dessa forma, vários estudos vêm sendo realizados, com intuito de revelar novos avanços na avaliação e tratamento do congelamento da marcha, devido ser um sintoma difícil para ser avaliado com precisão, por meio da observação, visto que os resultados obtidos acabam sendo subjetivos, apenas com base em relatos dos pacientes (MANCINI et al., 2017). Além disso, é um sintoma episódico e pode desaparecer durante a avaliação clínica devido a portador estar atento na sua marcha (BARTHEL et al., 2016). ...
... We observed the associations between the clinical characteristics such as the UPDRS total and UPDRS III scores, Hoehn and Yahr stage, PIGD score, and NFOGQ score, and the selected features during the 360° turning task. Although our result was similar to the findings of the previous studies on the associations between the severity of PD and turning characteristics [57][58][59][60], most studies employed small sample sizes and often did not control for confounders that may affect the turning characteristics owing to physical characteristics such as age, sex, height, and BMI. In addition, the previous studies assessed the clinical characteristics in the "On" state of medication [58,60], whereas this study assessed the clinical characteristics and turning task of people with PD in the "Off " state of medication. ...
Background
Freezing of gait (FOG) is a sensitive problem, which is caused by motor control deficits and requires greater attention during postural transitions such as turning in people with Parkinson’s disease (PD). However, the turning characteristics have not yet been extensively investigated to distinguish between people with PD with and without FOG (freezers and non-freezers) based on full-body kinematic analysis during the turning task. The objectives of this study were to identify the machine learning model that best classifies people with PD and freezers and reveal the associations between clinical characteristics and turning features based on feature selection through stepwise regression.
Methods
The study recruited 77 people with PD (31 freezers and 46 non-freezers) and 34 age-matched older adults. The 360° turning task was performed at the preferred speed for the inner step of the more affected limb. All experiments on the people with PD were performed in the “Off” state of medication. The full-body kinematic features during the turning task were extracted using the three-dimensional motion capture system. These features were selected via stepwise regression.
Results
In feature selection through stepwise regression, five and six features were identified to distinguish between people with PD and controls and between freezers and non-freezers (PD and FOG classification problem), respectively. The machine learning model accuracies revealed that the random forest (RF) model had 98.1% accuracy when using all turning features and 98.0% accuracy when using the five features selected for PD classification. In addition, RF and logistic regression showed accuracies of 79.4% when using all turning features and 72.9% when using the six selected features for FOG classification.
Conclusion
We suggest that our study leads to understanding of the turning characteristics of people with PD and freezers during the 360° turning task for the inner step of the more affected limb and may help improve the objective classification and clinical assessment by disease progression using turning features.
... To obtain freezing of gait measures, participants were videotaped by performing 2 freezing of gait provoking tests: the Ziegler test [41] and the turn-in-place test [42]. In the Ziegler test, participants began in a seated position 3.4 m from a closed door. ...
Background: Despite optimal medical and surgical intervention, freezing of gait commonly occurs in people with Parkinson disease. Action observation via video self-modeling, combined with physical practice, has potential as a noninvasive intervention to reduce freezing of gait.
Objective: The aim of this study is to determine the feasibility and acceptability of a home-based, personalized video self-modeling intervention delivered via a virtual reality head-mounted display (HMD) to reduce freezing of gait in people with Parkinson disease. The secondary aim is to investigate the potential effect of this intervention on freezing of gait, mobility, and anxiety.
Methods: The study was a single-group pre-post mixed methods pilot trial for which 10 participants with Parkinson disease and freezing of gait were recruited. A physiotherapist assessed the participants in their homes to identify person-specific triggers of freezing and developed individualized movement strategies to overcome freezing of gait. 180° videos of the participants successfully performing their movement strategies were created. Participants watched their videos using a virtual reality HMD, followed by physical practice of their strategies in their own homes over a 6-week intervention period. The primary outcome measures included the feasibility and acceptability of the intervention. Secondary outcome measures included freezing of gait physical tests and questionnaires, including the Timed Up and Go Test, 10-meter walk test, Goal Attainment Scale, and Parkinson Anxiety Scale.
Results: The recruitment rate was 24% (10/42), and the retention rate was 90% (9/10). Adherence to the intervention was high, with participants completing a mean of 84% (SD 49%) for the prescribed video viewing and a mean of 100% (SD 56%) for the prescribed physical practice. One participant used the virtual reality HMD for 1 week and completed the rest of the intervention using a flat-screen device because of a gradual worsening of his motion sickness. No other adverse events occurred during the intervention or assessment. Most of the participants found using the HMD to view their videos interesting and enjoyable and would choose to use this intervention to manage their freezing of gait in the future. Five themes were constructed from the interview data: reflections when seeing myself, my experience of using the virtual reality system, the role of the virtual reality system in supporting my learning, developing a deeper understanding of how to manage my freezing of gait, and the impact of the intervention on my daily activities. Overall, there were minimal changes to the freezing of gait, mobility, or anxiety measures from baseline to postintervention, although there was substantial variability between participants. The intervention showed potential in reducing anxiety in participants with high levels of anxiety.
Conclusions: Video self-modeling using an immersive virtual reality HMD plus physical practice of personalized movement strategies is a feasible and acceptable method of addressing freezing of gait in people with Parkinson disease.
... Freezing of gait is a symptom commonly observed in the moderate to advanced stages of Parkinson's disease and defined as "brief, episodic absence or marked reduction of forward progression of the feet despite the intention to walk." 1 . Turning is typically considered to be difficult for individuals with Parkinson's disease and to be the most sensitive trigger of freezing-of-gait episodes 2,3 . The unpredictable occurrences of freezing-of-gait episodes during turning lead to a high risk of falls and may cause fall-related fractures 4 . ...
Background
Individuals with Parkinson disease can experience freezing of gait: a sudden, brief episode of an inability to move their feet despite the intention to walk . Since turning is the most sensitive condition to provoke freezing-of-gait episodes, and the eyes typically lead turning, we hypothesize that disturbances in saccadic eye movements are related to freezing-of-gait episodes.
Objectives
This study explores the relationship between freezing-of-gait episodes and saccadic eye movements for gaze shift and gaze stabilization during turning.
Methods
We analyzed 277 freezing-of-gait episodes provoked among 17 individuals with Parkinson disease during two conditions: self-selected speed and rapid speed 180-degree turns in alternating directions. Eye movements acquired from electrooculography signals were characterized by the average position of gaze, the amplitude of gaze shifts, and the speed of gaze stabilization. We analyzed these variables before and during freezing-of-gait episodes occurring at the different phase angles of a turn.
Results
Significant off-track changes of the gaze position were observed almost one 180-degree-turn time before freezing-of-gait episodes. In addition, the speed of gaze stabilization significantly decreased during freezing-of-gait episodes.
Conclusions
We argue that off-track changes of the gaze position could be a predictor of freezing-of-gait episodes due to continued failure in movement-error correction or an insufficient preparation for eye-to-foot coordination during turning. The decline in the speed of gaze stabilization is large during freezing-of-gait episodes given the slowness or stop of body turning. We argue that this could be evidence for a healthy compensatory system in individuals with freezing-of-gait.
... FOG has been associated with disease severity (Perez-Lloret et al., 2014). Accordingly, when normally distributed, an analysis of covariance (ANCOVA) with a covariate of MDS-UPDRS-III score was additionally performed to examine the differences in gait parameters between PD + FOG and PD − FOG whilst adjusting for the disease severity, following the method in a previous study (Mancini et al., 2017). ...
Freezing of gait (FOG) appears to be associated with increased risk of forward falls in patients with Parkinson's disease (PD). This study aimed to experimentally validate forward gait instability in PD patients with FOG (PD + FOG). Eleven PD + FOG patients, 9 PD patients without FOG (PD - FOG), and 13 healthy controls participated. Self-selected paced gait was analyzed by a three-dimensional motion-capture analysis system. We assessed the distance between the center of mass and the base of support (COM-BOS distance) and the margin of stability (MOS), considering the position and velocity of the COM as gait stability parameters, spatiotemporal gait parameters and kinematic parameters. The anteroposterior COM-BOS distance was smaller in PD + FOG patients than in PD-FOG patients and controls. Anteroposterior MOS was larger in PD + FOG and PD-FOG patients than controls (p < 0.05). PD + FOG patients showed smaller anteroposterior MOS than PD-FOG patients, when adjusting for disease severity (p < 0.05). Only in the PD + FOG group, when adjusting for disease severity, step length was positively correlated with the anteroposterior COM-BOS distance (p < 0.05), and cadence was negatively correlated with the anteroposterior MOS (p < 0.05). These results indicated that PD patients with FOG have forward gait instability and suggested that such instability may be associated with reduced step length and increased cadence.
... Freezing of gait (FOG), often defined as a feeling of one's feet being "glued" to the floor [1,2], is a debilitating phenomenon in Parkinson's disease (PD) that negatively impacts quality of life and can lead to falls, serious injury, or even death [3][4][5][6]. FOG is a challenging phenomenon to objectively measure in the clinic and laboratory [7], but several tasks, such as 360-degree turning in place [8], the turning and barrier course (TBC) [9], and stepping in place (SIP) [10], have been developed to safely and reliably elicit FOG. ...
Freezing of gait (FOG), a debilitating symptom of Parkinson’s disease (PD), can be safely studied using the stepping in place (SIP) task. However, clinical, visual identification of FOG during SIP is subjective and time consuming, and automatic FOG detection during SIP currently requires measuring center of pressure on dual force plates. This study examines whether FOG elicited during SIP in 10 individuals with PD could be reliably detected using kinematic data measured from wearable inertial measurement unit sensors (IMUs). A general, logistic regression model (AUC = 0.81) determined that three gait parameters together were overall the most robust predictors of FOG during SIP: arrhythmicity, swing time coefficient of variation, and swing angular range. Participant-specific models revealed varying sets of gait parameters that best predicted FOG for each participant, highlighting variable FOG behaviors, and demonstrated equal or better performance for 6 out of the 10 participants, suggesting the opportunity for model personalization. The results of this study demonstrated that gait parameters measured from wearable IMUs reliably detected FOG during SIP, and the general and participant-specific gait parameters allude to variable FOG behaviors that could inform more personalized approaches for treatment of FOG and gait impairment in PD.
... Measures of feasibility included recruitment rate, retention rate, adherence to the intervention (by recording the number of daily video viewings and physical practice) using self-report logbooks and adverse events associated with the intervention. Measures of acceptability included a modified Players Experience of Need Satisfaction questionnaire (PENS) 37 To obtain freezing of gait measures, participants were videotaped performing two freezing of gait provoking tests; the Ziegler test 39 and the turn-in-place test 40 ...
Background:
Despite optimal medical and/or surgical intervention, freezing of gait occurs commonly in people with Parkinson’s disease, leading to reduced mobility, falls, poor quality of life and increased healthcare costs. Action observation via video self-modelling, combined with physical practice, has potential as a non-invasive intervention to reduce freezing of gait.
Objective:
To determine the feasibility and acceptability of a home-based, personalised video self-modelling intervention delivered via a virtual reality head mounted display to reduce freezing of gait in people with Parkinson’s disease. Secondary aims included investigating the potential effect of this intervention on freezing of gait, mobility and anxiety.
Methods:
A single group pre/post mixed methods pilot trial. Ten participants with Parkinson’s disease and freezing of gait were recruited. A physiotherapist assessed participants in their homes to identify person-specific triggers of freezing and developed individualised movement strategies to overcome freezing of gait. 180-degree videos of participants successfully performing their movement strategies were created. Participants watched their videos using a virtual reality head mounted display, followed by physical practice of their strategies in their own homes over a six-week intervention period. Primary outcome measures included feasibility and acceptability of the intervention. Secondary outcome measures included freezing of gait physical tests and questionnaires, Timed Up and Go test, 10m walk test, Goal Attainment Scale, and Parkinson Anxiety Scale.
Results:
Ten participants were recruited. The recruitment rate was 24% and retention rate was 90%. Adherence to the intervention was high, with participants completing a mean of 84% for the prescribed video viewing and a mean of 100% for the prescribed physical practice. One participant used the virtual reality head mounted display for one week and completed the rest of the intervention using a flatscreen device due to a gradual worsening of his motion sickness. No other adverse events occurred during the intervention or assessments. Most participants found using the head mounted display to view their videos interesting and enjoyable and would choose to use this intervention to manage their freezing of gait in the future. Five themes were constructed from interview data: reflections when seeing myself; my experience of using the virtual reality system; the role of the virtual reality system in supporting my learning; developing a deeper understanding on how to manage my freezing of gait; and impact of the intervention on my daily activities. Overall, there were minimal changes to the freezing of gait, mobility or anxiety measures from baseline to post-intervention, although there was substantial variability between participants. The intervention showed potential in reducing anxiety in participants with high levels of anxiety.
Conclusions:
Video self-modelling using an immersive virtual reality head mounted display plus physical practice of personalised movement strategies is a feasible and acceptable method of addressing freezing of gait in people with Parkinson’s disease. Clinical Trial: Australian New Zealand Clinical Trials Registry (ANZCTR12619000139178)
... The new FOG-Q has been recently found to be unreliable and not responsive to small effect sizes [7]. Measures that rely on capturing a FOG episode in the laboratory (direct measures) [8][9][10][11][12], are limited by the inherent variability of each episode, therefore a captured episode may not be representative of overall FOG severity. Furthermore, approaches to reliably trigger an episode have not been established. ...
Background: Freezing of gait (FOG) is notoriously difficult to quantify, leading to multiple metrics utilized as outcomes for clinical trials. The instrumented timed up a go and the many parameters that can be derived from it are commonly used as objective markers of gait severity in FOG trials, however it is unknown if they represent FOG severity.
Objective: To determine the specificity and responsiveness of objective surrogate markers of FOG severity commonly utilized in FOG studies.
Methods: Markers compared included: velocity, step/stride length, step/stride length variability, TUG, and turn duration. Data was collected in four conditions (ON and OFF dopaminergic drugs, with and without a dual task). Unified Parkinson’s Disease rating scale (UPDRS) was administered in the ON and OFF states.
Results: 33 subjects were recruited (17 PD subjects without FOG (PD-control), and 16 subjects with PD and dopa-responsive FOG PD-FOG). The UPDRS motor scores were: 24.9 for the PD-control group in the ON state, 24.8 for the FOG group in the ON state, 42.4 for the FOG group in the OFF state. Significant mean differences between the ON and OFF conditions were observed with all surrogate markers (p<0.01). However, only dual task turn duration and step variability showed trends toward significance when comparing PD-control and ON-FOG (p=0.08). Test-retest reliability was high (ICC >0.90) for all markers except standard deviations. Step length variability was the only marker to show an area under the ROC curve analysis >0.70 comparing ON-FOG vs. PD-control.
Conclusions: Multiple candidate surrogate markers for FOG severity showed responsiveness to levodopa challenge, however, most were not specific for FOG severity.
... So far, no gold standard exists to diagnose FOG and to measure FOG severity. Different approaches have been used such as self-reported measures using questionnaires [5], FOG provoking gait trajectories [6], or instrumented analysis with the use of wearable sensors [7]. In clinical routine, there can be a high false negative rate of patients subjectively reporting FOG which is not visible during the visit and thus not measured objectively. ...
Freezing of gait (FOG) in Parkinson’s disease (PD) is a highly disabling symptom which impacts quality of life. The New FOG Questionnaire (NFOG-Q) is the most commonly used tool worldwide to characterize FOG severity in PD. This study aims to provide a German translation of the NFOG-Q and to assess its validity in people with PD. The questionnaire was translated using forward-backward translation. Validity was tested in 57 PD patients with FOG via Cronbach’s alpha for internal consistency and Spearman correlations with several clinical measures to quantify disease severity, mobility, fall risk, and cognitive state for convergent and divergent validity. The German version of the NFOG-Q shows good internal consistency (Cα = 0.84). Furthermore, the NFOG-Q score was significantly correlated with the MDS-UPDRS III, H&Y stage, Timed Up and Go test, and the subjective fear of falling (FES-I). The lack of correlation with cognition (MoCA) points towards good divergent validity. This study provides a German version of the NFOG-Q which proved to be valid for the assessment of FOG severity in individuals with PD.
... It has been shown that freezing is usually accompanied by high-frequency leg movements [4]. Recently a 'Freezing Ratio' was defined as the power in the "freeze band" (3.5-8 Hz) divided by the power in the "locomotor band" (0.5-3 Hz) with larger ratios indicating more freezing [43,44]. Such 'high-frequency' components of gait have been associated with the 'trembling' observed during freezing episodes. ...
Abstract Background Although a growing number of studies focus on the measurement and detection of freezing of gait (FoG) in laboratory settings, only a few studies have attempted to measure FoG during daily life with body-worn sensors. Here, we presented a novel algorithm to detect FoG in a group of people with Parkinson’s disease (PD) in the laboratory (Study I) and extended the algorithm in a second cohort of people with PD at home during daily life (Study II). Methods In Study I, we described of our novel FoG detection algorithm based on five inertial sensors attached to the feet, shins and lumbar region while walking in 40 participants with PD. We compared the performance of the algorithm with two expert clinical raters who scored the number of FoG episodes from video recordings of walking and turning based on duration of the episodes: very short ( 5 s). In Study II, a different cohort of 48 people with PD (with and without FoG) wore 3 wearable sensors on their feet and lumbar region for 7 days. Our primary outcome measures for freezing were the % time spent freezing and its variability. Results We showed moderate to good agreement in the number of FoG episodes detected in the laboratory (Study I) between clinical raters and the algorithm (if wearable sensors were placed on the feet) for short and long FoG episodes, but not for very short FoG episodes. When extending this methodology to unsupervised home monitoring (Study II), we found that percent time spent freezing and the variability of time spent freezing differentiated between people with and without FoG (p
Background:
The "gold standard" marker for freezing of gait severity is percentage of time spent with freezing observed through video analysis.
Objective:
This study examined inter- and intra-rater reliability and variability of physiotherapists rating freezing of gait severity through video analysis and explored the effects of experience.
Methods:
Thirty physiotherapists rated 14 videos of Timed Up and Go performance by people with Parkinson's and gait freezing. Ten videos were unique, while four were repeated. Freezing frequency, total duration, and percentage of time spent with freezing were computed. Reliability and variability were estimated using ICC (2,1) and mean absolute differences. Between-group differences were calculated with the one-way ANOVA.
Results:
Inter- and intra-rater reliability ranged from moderate to good (ICC: inter-rater frequency = 0.63, duration = 0.78, percentage = 0.50; intra-rater frequency = 0.84, duration = 0.89, percentage = 0.50). Variability for freezing frequency was two episodes. Inter- and intra-rater variability for total freezing duration was 18.8 and 12.3 seconds, respectively. For percentage of time spent with freezing, this was 15.2% and 13.5%. Physiotherapy experience had no effect.
Conclusion:
Physiotherapists demonstrated sufficient reliability, but variability was large enough to cause changes in severity classifications on existing rating scales. Percentage of time spent with freezing was the least reliable marker, supporting the use of freezing frequency or total duration instead.
Background:
Freezing of gait (FOG) is a debilitating, variably expressed motor symptom in people with Parkinson's disease (PwPD) with limited treatments.
Objective:
To determine if the rate of progression in spatiotemporal gait parameters in people converting from a noFOG to a FOG phenotype (FOGConv) was faster than non-convertors, and determine if gait parameters can help predict this conversion.
Methods:
PwPD were objectively monitored longitudinally, approximately every 6 months. Non-motor assessments were performed at the initial visit. Steady-state gait in the levodopa ON-state was collected using a gait mat (Protokinetics) at each visit. The rate of progression in 8 spatiotemporal gait parameters was calculated. FOG convertors (FOGConv) were classified if they did not have FOG at initial visit and developed FOG at a subsequent visit.
Results:
Thirty freezers (FOG) and 30 non-freezers were monitored an average of 3.5 years, with 10 non-freezers developing FOG (FOGConv). FOGConv and FOG had faster decline in mean stride-length, swing-phase-percent, and increase in mean total-double-support percent, coefficient of variability (CV) foot-strike-length and CV swing-phase-percent than the remaining non-freezers (noFOG). On univariate modeling, progression rates of mean stride-length, stride-velocity, swing-phase-percent, total-double-support-percent and of CV swing-phase-percent had high discriminative power (AUC > 0.83) for classification of the FOGConv and noFOG groups.
Conclusion:
FOGConv had a faster temporal decline in objectively quantified gait than noFOG, and progression rates of spatiotemporal gait parameters were more predictive of FOG phenotype conversion than initial (static) parameters Objectively monitoring gait in disease prediction models may help define FOG prone groups for testing putative treatments.
Objective:
We investigated changes in indices of muscle synergies prior to gait initiation and the effects of gaze shift in patients with Parkinson's disease (PD). A long-term objective of the study is to develop a method for quantitative assessment of gait-initiation problems in PD.
Methods:
PD patients without clinical signs of postural instability and two control groups (age-matched and young) performed a gait initiation task in a self-paced manner, with and without a quick prior gaze shift produced by turning the head. Muscle groups with parallel scaling of activation levels (muscle modes) were identified as factors in the muscle activation space. Synergy index stabilizing center of pressure trajectory in the anterior-posterior and medio-lateral directions (indices of stability) was quantified in the muscle mode space. A drop in the synergy index in preparation to gait initiation (anticipatory synergy adjustment, ASA) was quantified.
Results:
Compared to the control groups, PD patients showed significantly smaller synergy indices and ASA for both directions of the center of pressure shift. Both PD and age-matched controls, but not younger controls, showed detrimental effects of the prior gaze shift on the ASA indices.
Conclusions:
PD patients without clinically significant posture or gait disorders show impaired stability of the center of pressure and its diminished adjustment during gait initiation.
Significance:
The indices of stability and ASA may be useful to monitor pre-clinical gait disorders, and lower ASA may be relevant to emergence of freezing of gait in PD.
Introduction:
People with Parkinson's disease (PD) with freezing of gait (FOG; freezers) show impaired dynamic balance and experience falls more frequently compared to those without (non-freezers). Here, we explore the neural underpinnings of these freezing-related balance problems.
Methods:
12 freezers, 16 non-freezers and 14 controls performed a dynamic balance task in the lab. The next day, the same task was investigated in the MRI-scanner through motor imagery (MI). A visual imagery (VI) control task was also performed. Imagery engagement was determined by comparing the performance times between the dynamic balance task, and its MI- and VI-variants. Balance-related brain activations in regions of interest were contrasted between groups based on an MI > rest versus VI > rest contrast.
Results:
Freezers and non-freezers were matched for age, cognition and disease severity. Similar performance times between the balance control task and the MI-conditions revealed excellent imagery engagement. Compared to non-freezers, freezers showed decreased activation in regions of interest located in the left mesencephalic locomotor region (MLR; p = 0.006), right anterior cerebellum (p = 0.017) and cerebellar vermis (p < 0.001). Intriguingly, non-freezers showed higher activations in the cerebellar vermis than controls (p = 0.010).
Conclusion:
Overall, we showed that decreased activation in the left MLR, and cerebellar regions in freezers relative to non-freezers could explain why dynamic balance is more affected in freezers. As non-freezers displayed increased cerebellar vermis activation compared to controls, it is possible that freezers show an inability to recruit sufficient compensatory cerebellar activity for effective dynamic balance control.
Purpose
To summarize the effects of rehabilitation interventions to reduce freezing of gait (FOG) in people with Parkinson’s disease.
Methods
A systematic review with meta-analyses of randomized trials of rehabilitation interventions that reported a FOG outcome was conducted. Quality of included studies and certainty of FOG outcome were assessed using the PEDro scale and GRADE framework.
Results
Sixty-five studies were eligible, with 62 trialing physical therapy/exercise, and five trialing cognitive and/or behavioral therapies. All meta-analyses produced very low-certainty evidence. Physical therapy/exercise had a small effect on reducing FOG post-intervention compared to control (Hedges’ g= −0.26, 95% CI= −0.38 to −0.14, 95% prediction interval (PI)= −0.38 to −0.14). We are uncertain of the effects on FOG post-intervention when comparing: exercise with cueing to without cueing (Hedges’ g= −0.58, 95% CI= −0.86 to −0.29, 95% PI= −1.23 to 0.08); action observation training plus movement strategy practice to practice alone (Hedges’ g= −0.56, 95% CI= −1.16 to 0.05); and dance to multimodal exercises (Hedges’ g= −0.64, 95% CI= −1.53 to 0.25).
Conclusions
We are uncertain if physical therapy/exercise, cognitive or behavioral therapies, are effective at reducing FOG.
•
Implications for rehabilitation
• FOG leads to impaired mobility and falls, but the effect of rehabilitation interventions (including physical therapy/exercise and cognitive/behavioral therapies) on FOG is small and uncertain.
• Until more robust evidence is generated, clinicians should assess FOG using both self-report and physical measures, as well as other related impairments such as cognition, anxiety, and fear of falling.
• Interventions for FOG should be personalized based on the individual’s triggers and form part of a broader exercise program addressing gait, balance, and falls prevention.
• Interventions should continue over the long term and be closely monitored and adjusted as individual circumstances change.
Objectives
There is no standardisation of tasks or measures for evaluation of freezing of gait severity in people with Parkinson's disease. This study aimed to develop a clinician-rated tool for freezing of gait severity (i.e. Freezing of Gait Severity Tool), through determining clinicians’ ratings of the most important triggering circumstances to be examined and aspects of freezing of gait to be measured.
Design
A three-round, web-based Delphi study.
Participants
Healthcare professionals, with at least five years’ experience in managing freezing of gait in people with Parkinson.
Main outcome measures
Round 1 required participants ( n = 28) to rate items on a 5-point Likert scale, based on priority for inclusion in the Freezing of Gait Severity Tool. In Round 2, participants ( n = 18) ranked the items based on priority for inclusion. In Round 3, participants ( n = 18) confirmed or rejected the shortlisted items by judging their ability, on a binary scale, to screen for freezing of gait, detect changes in freezing severity, and discriminate between degrees of severity.
Results
Participants agreed with the triggering circumstances of turning hesitation, narrow space hesitation, start hesitation, cognitive dual-tasking, and open space hesitation should be assessed; and the aspects of gait freezing to be measured included freezing type, number of freezing episodes during a task, and average duration of freezing episodes.
Conclusions
This study attained a consensus for the items to be included in a clinician-rated tool for freezing of gait severity. Future studies should investigate psychometric properties and clinical feasibility of the Freezing of Gait Severity Tool.
Background:
Freezing of gait (FOG) is a complex symptom in Parkinson's disease (PD) that is both elusive to elicit and varied in its presentation. These complexities present a challenge to measuring FOG in a sensitive and reliable way, precluding therapeutic advancement.
Objective:
We investigated the reliability, validity, and responsiveness of manual video annotations of the turning-in-place task and compared it to the sensor-based FOG ratio.
Methods:
Forty-five optimally medicated people with PD and FOG performed rapid alternating 360° turns without and with an auditory stroop dual task, thrice over two consecutive days. The tasks were video recorded, and inertial sensors were placed on the lower back and shins. Interrater reliability between three raters, criterion validity with self-reported FOG, and responsiveness to single-session split-belt treadmill (SBT) training were investigated and contrasted with the sensor-based FOG ratio.
Results:
Visual ratings showed excellent agreement between raters for the percentage time frozen (%TF) (ICC [intra-class correlation coefficient] = 0.99), the median duration of a FOG episode (ICC = 0.90), and the number of FOG episodes (ICC = 0.86). Dual tasking improved the sensitivity and validity of visual FOG ratings resulting in increased FOG detection, criterion validity with self-reported FOG ratings, and responsiveness to a short SBT intervention. The sensor-based FOG ratio, on the contrary, showed complex FOG presentation-contingent relationships with visual and self-reported FOG ratings and limited responsiveness to SBT training.
Conclusions:
Manual video annotations of FOG during dual task turning in place generate reliable, valid, and sensitive outcomes for investigating therapeutic effects on FOG. © 2021 International Parkinson and Movement Disorder Society.
Background
Turning is a common trigger for freezing episodes in patients with Parkinson’s disease (PD). Freezing during turning can lead to falls and fractures and decreased quality of life.
Research question
Does foot-strike contact variability also increase during turning, as previously reported in straight gait in PD patients with Freezing of Gait (FOG)?
Methods
Subjects were instructed to walk on a gait mat, making “normal pivot” (180°) turns at each end. ProtoKinetics Movement Analysis Software (PKMAS) software was used for analysis. Video recordings and foot-pressure-prints were studied to identify and define turn segments. Spatiotemporal gait and turn measures were then determined only for the turn segments. A movement disorders neurologist determined clinical freezes.
Results
100 subjects (28 controls, 38 noFOG and 34 FOG) were included. Compared to non-freezers (noFOG), FOG subjects had a smaller foot-strike during turning (a measure of completeness of foot contact with the mat) and increased foot-strike variability. FOG subjects also had a shorter stride-length, slower stride-velocity, and greater swing phase time and percentage during turns. After adjusting for turn direction, inner/outer leg dynamics showed heavier inner leg footsteps in FOG subjects. 38% of FOG subjects experienced freezes during turning. 69% of freezes occurred during the middle third of the turn. Turn-freezers had more severe spatiotemporal gait deficits.
Significance
Developing targeted therapies to retrain subjects to plant their whole foot on the ground with more consistency could help decrease episodes of freezing of gait.
This chapter is concerned with the use of wearable devices for disabled and extreme sports. These sporting disciplines offer unique challenges for sports scientists and engineers. Disabled athletes often rely on and utilize more specialist equipment than able-bodied athletes. Wearable devices could be particularly useful for monitoring athlete-equipment interactions in disability sport, with a view to improving comfort and performance, while increasing accessibility and reducing injury risks. Equipment also tends to be key for so called “extreme” sports, such as skiing, snowboarding, mountain biking, bicycle motocross, rock climbing, surfing, and white-water kayaking. These sports are often practiced outdoors in remote and challenging environments, with athletes placing heavy demands on themselves and their equipment. Extreme sports also encompass disability sports, like sit skiing and adaptive mountain biking, and the popularity and diversity of such activities is likely to increase with improvements in technology and training, as well as with the support of organizations like the High Fives Foundation (highfivesfoundation.org) and Disability Snowsport, United Kingdom (disabilitysnowsport.org.uk). Within this chapter in these two sporting contexts, wearable devices are broadly associated with those that can be used to monitor the kinetics and kinematics of an athlete and their equipment. This chapter will first consider image-based alternatives and then focus on wearable sensors, in three main sections covering, (1) sports wearables, (2) disability sport and the use of wearables, and (3) extreme sport and the use of wearables, as well as making recommendations for the future.
As clinical characterization of mobility abnormalities can be highly dependent on examiners’ expertise, wearable technologies have the potential to access aspects of mobility measured in free-living. Over the past 20 years, advances in wireless and miniaturized technologies have emerged as viable tools to move from laboratory-based measures of mobility to free-living. In fact, as it is known that patients with various conditions do paradoxically well when they know that they are being observed, unobtrusive home monitoring has the untapped potential to provide quantitative mobility measures that may be even more sensitive markers of subtle changes, compared to measures in the laboratory. This chapter will provide an overview of the potential uses, benefits, and obstacles of utilizing wearable technology for assessment of mobility in clinical populations.
Introduction
Cholinergic dysfunction contributes to mobility deficits in Parkinson’s disease (PD). People with PD rely on limited prefrontal executive-attentional resources for the control of locomotion, including turning. Cortical and behavioral responses to cholinergic augmentation during turning remains unclear. We examined prefrontal cortex (PFC) activity while turning-in-place and spatiotemporal measures of turns in response to usual dopaminergic medication and adjunct cholinergic augmentation.
Methods
This study consisted of a single-site, randomized, double-blind crossover trial. Twenty PD participants were assessed in the levodopa-off state and then randomized to either levodopa + donepezil (5 mg) or levodopa + placebo treatments for two weeks followed by a 2-week washout before crossover. The primary outcome was change from off state in PFC activity while turning-in-place (assessed with functional near-infrared spectroscopy). Secondary outcomes were changes in spatiotemporal turning measures (assessed with body-worn inertial measurement units) and accuracy in the secondary task.
Results
Nineteen participants completed the trial. While levodopa + placebo had no effect on PFC activity when turning-in-place with a dual-task, levodopa + donepezil led to a large reduction in PFC activity (effect size, -0.82). Spatiotemporal measures of turning improved with both treatments, with slightly greater effect sizes observed for levodopa + donepezil. Additionally, the accuracy in the concurrent cognitive task improved only with levodopa + donepezil (effect size, 0.63).
Conclusion
The addition of cholinergic therapy with donepezil (5 mg/day for 2 weeks) to standard dopaminergic therapy reduced the burden on prefrontal executive-attentional resources while turning with a dual-task and improved secondary task accuracy and turning.
Freezing of gait is a common and disabling symptom in patients with parkinsonism, characterised by sudden and brief episodes of inability to produce effective forward stepping. These episodes typically occur during gait initiation or turning. Treatment is important because freezing of gait is a major risk factor for falls in parkinsonism, and a source of disability to patients. Various treatment approaches exist, including pharmacological and surgical options, as well as physiotherapy and occupational therapy, but evidence is inconclusive for many approaches, and clear treatment protocols are not available. To address this gap, we review medical and non-medical treatment strategies for freezing of gait and present a practical algorithm for the management of this disorder, based on a combination of evidence, when available, and clinical experience of the authors. Further research is needed to formally establish the merits of our proposed treatment protocol.
Copyright © 2015 Elsevier Ltd. All rights reserved.
Freezing of gait is a disabling symptom of Parkinson's disease that causes a paroxysmal cessation of normal footsteps while walking. Despite a great deal of empirical research, the pathophysiological mechanisms underlying the symptom remain unclear. In this targeted review, we synthesize recent insights from research into freezing in an effort to clarify the neurobiological basis of this phenomenon. We conclude that freezing manifests via a common neural pathway in which transient increases in inhibitory basal ganglia output lead to decreased activity within the brainstem structures that coordinate gait. This cascade may be triggered through dopaminergic depletion in the striatum and over-activity within the subthalamic nucleus. These insights may benefit both the diagnostic and therapeutic management of freezing in Parkinson's disease.
Freezing of Gait (FOG) is a disabling motor symptom experienced by a large proportion of patients with Parkinson's disease (PD). Whilst it is known that FOG contributes to lower health-related quality of life (HRQoL), previous studies have not accounted for other important factors when measuring the specific impact of this symptom. The aim of this study was to examine FOG and HRQoL whilst controlling for other factors that are known to impact patient wellbeing, including cognition, motor severity, sleep disturbance and mood. Two hundred and three patients with idiopathic PD (86 with FOG) were included in the study. All patients were between Hoehn & Yahr stages I-III. A forced entry multiple regression model evaluating the relative contribution of all symptoms was conducted, controlling for time since diagnosis and current dopaminergic treatment. Entering all significantly correlated variables into the regression model accounted for the majority of variance exploring HRQoL. Self-reported sleep-wake disturbances, depressive and anxious symptoms and FOG were individually significant predictors. FOG accounted for the highest amount of unique variance. Whilst sleep-wake disturbance and mood have a significant negative impact on HRQoL in PD, the emergence of FOG represents the most substantial predictor amongst patients in the earlier clinical stages of disease. This finding presumably reflects the disabling loss of independence and fear of injury associated with FOG and underlines the importance of efforts to reduce this common symptom.
Freezing of gait (FoG) is a transient inability to initiate or maintain stepping that often accompanies advanced Parkinson's disease (PD) and significantly impairs mobility. The current study uses a multimodal neuroimaging approach to assess differences in the functional and structural locomotor neural network in PD patients with and without FoG and relates these findings to measures of FoG severity. Twenty-six PD patients and fifteen age-matched controls underwent resting-state functional magnetic resonance imaging and diffusion tensor imaging along with self-reported and clinical assessments of FoG. After stringent movement correction, fifteen PD patients and fourteen control participants were available for analysis. We assessed functional connectivity strength between the supplementary motor area (SMA) and the following locomotor hubs: 1) subthalamic nucleus (STN), 2) mesencephalic and 3) cerebellar locomotor region (MLR and CLR, respectively) within each hemisphere. Additionally, we quantified structural connectivity strength between locomotor hubs and assessed relationships with metrics of FoG. FoG+ patients showed greater functional connectivity between the SMA and bilateral MLR and between the SMA and left CLR compared to both FoG- and controls. Importantly, greater functional connectivity between the SMA and MLR was positively correlated with i) clinical, ii) self-reported and iii) objective ratings of freezing severity in FoG+, potentially reflecting a maladaptive neural compensation. The current findings demonstrate a re-organization of functional communication within the locomotor network in FoG+ patients whereby the higher-order motor cortex (SMA) responsible for gait initiation communicates with the MLR and CLR to a greater extent than in FoG- patients and controls. The observed pattern of altered connectivity in FoG+ may indicate a failed attempt by the CNS to compensate for the loss of connectivity between the STN and SMA and may reflect a loss of lower-order, automatic control of gait by the basal ganglia.
Freezing of gait is one of the most debilitating symptoms in Parkinson's disease as it causes falls and reduces mobility and quality of life. The pedunculopontine nucleus is one of the major nuclei of the mesencephalic locomotor region and has neurons related to anticipatory postural adjustments preceding step initiation as well as to the step itself, thus it may be critical for coupling posture and gait to avoid freezing. Because freezing of gait and postural impairments have been related to frontal lesions and frontal dysfunction such as executive function, we hypothesized that freezing is associated with disrupted connectivity between midbrain locomotor regions and medial frontal cortex. We used diffusion tensor imaging to quantify structural connectivity of the pedunculopontine nucleus in patients with Parkinson's disease with freezing of gait, without freezing, and healthy age-matched controls. We also included behavioural tasks to gauge severity of freezing of gait, quantify gait metrics, and assess executive cognitive functions to determine whether between-group differences in executive dysfunction were related to pedunculopontine nucleus structural network connectivity. Using seed regions from the pedunculopontine nucleus, we were able to delineate white matter connections between the spinal cord, cerebellum, pedunculopontine nucleus, subcortical and frontal/prefrontal cortical regions. The current study is the first to demonstrate differences in structural connectivity of the identified locomotor pathway in patients with freezing of gait. We report reduced connectivity of the pedunculopontine nucleus with the cerebellum, thalamus and multiple regions of the frontal cortex. Moreover, these structural differences were observed solely in the right hemisphere of patients with freezing of gait. Finally, we show that the more left hemisphere-lateralized the pedunculopontine nucleus tract volume, the poorer the performance on cognitive tasks requiring the initiation of appropriate actions and/or the inhibition of inappropriate actions, specifically within patients with freezing. These results support the notion that freezing of gait is strongly related to structural deficits in the right hemisphere's locomotor network involving prefrontal cortical areas involved in executive inhibition function.
Freezing of gait (FOG) is defined as a brief, episodic absence or marked reduction of forward progression of the feet despite the intention to walk. It is one of the most debilitating motor symptoms in patients with Parkinson's disease (PD) as it may lead to falls and a loss of independence. The pathophysiology of FOG seems to differ from the cardinal features of PD and is still largely unknown. In the present paper, we review the studies that were performed since 2011 on methods to provoke and assess FOG and discuss new insights into behavioral and neural mechanisms underlying this clinical phenomenon. We conclude that most of the work reviewed confirms that gait pattern generation disturbances are central to FOG. The finding that FOG reflects a combined motor and cognitive de-automatization deficit, which may not be sufficiently offset by executive control, probably acts as parallel mechanism.
We have previously published a technique for objective assessment of freezing of gait (FOG) in Parkinson's disease (PD) from a single shank-mounted accelerometer. Here we extend this approach to evaluate the optimal configuration of sensor placement and signal processing parameters using seven sensors attached to the lumbar back, thighs, shanks and feet.
Multi-segmental acceleration data was obtained from 25 PD patients performing 134 timed up and go tasks, and clinical assessment of FOG was performed by two experienced raters from video. Four metrics were used to compare objective and clinical measures; the intraclass correlation coefficient (ICC) for number of FOG episodes and the percent time frozen per trial; and the sensitivity and specificity of FOG detection.
The seven-sensor configuration was the most robust, scoring highly on all measures of performance (ICC number of FOG 0.75; ICC percent time frozen 0.80; sensitivity 84.3%; specificity 78.4%). A simpler single-shank sensor approach provided similar ICC values and exhibited a high sensitivity to FOG events, but specificity was lower at 66.7%. Recordings from the lumbar sensor offered only moderate agreement with the clinical raters in terms of absolute number and duration of FOG events (likely due to musculoskeletal attenuation of lower-limb 'trembling' during FOG), but demonstrated a high sensitivity (86.2%) and specificity (82.4%) when considered as a binary test for the presence/absence of FOG within a single trial.
The seven-sensor approach was the most accurate method for quantifying FOG, and is best suited to demanding research applications. A single shank sensor provided measures comparable to the seven-sensor approach but is relatively straightforward in execution, facilitating clinical use. A single lumbar sensor may provide a simple means of objective FOG detection given the ubiquitous nature of accelerometers in mobile telephones and other belt-worn devices.
Over half of patients with PD eventually develop freezing of gait (FoG), an intermittent failure to initiate or maintain walking that is often associated with trembling of the legs. We tested 21 PD with FoG, 27 PD without FoG, and 21 healthy elderly people in a clinic with the Intrumented Timed Up and Go test (ITUG). FoG was quantified from the power spectral density of the antero-posterior shank acceleration from which a Frequency Ratio was calculated as the square of the total power in the 3-8 Hz band, divided by the square of the total power in the .5-3 Hz band. Spatiotemporal gait parameters calculated from synchronized gyroscopes on the two legs were also measured in these subjects. The Frequency Ratio was significantly larger in freezers than in non-freezers or control subjects. It better differentiated gait disorders between PD subjects with and without FoG than traditional gait measures such as stride length, stride velocity and double support time. The Frequency Ratio was validated as significantly correlated with self-perceived severity of gait and balance confidence. This Freezing Ratio will be useful to quantify FoG during a simple ITUG, a popular clinical test of mobility.
After 20 years follow-up of newly diagnosed patients with Parkinson's disease (PD), 100 of 136 (74%) have died. The mortality rate fell in the first 3 years of treatment, then rose compared to the general population, the standardized mortality ratio from 15 to 20 years reaching 3.1. Drug induced dyskinesia and end of dose failure were experienced by most patients, but the main current problems relate to the non-levodopa responsive features of the disease. Dementia is present in 83% of 20-year survivors. Dementia correlates with increasing age and probably reflects an interplay of multiple pathologies. Seventeen people with dementia had postmortems. Eight had diffuse Lewy bodies as the only cause of dementia, while others had mixed neuropathology. Only one person lives independently and 48% are in nursing homes. Excessive daytime sleepiness is noted in 70%, falls have occurred in 87%, freezing in 81%, fractures in 35%, symptomatic postural hypotension in 48%, urinary incontinence in 71%, moderate dysarthria in 81%, choking in 48%, and hallucinations in 74%. The challenge is to understand the cellular mechanisms underlying the diverse features of advanced PD that go far beyond a lack of dopamine. © 2008 Movement Disorder Society
In this paper, we present a wearable assistant for Parkinson's disease (PD) patients with the freezing of gait (FOG) symptom. This wearable system uses on-body acceleration sensors to measure the patients' movements. It automatically detects FOG by analyzing frequency components inherent in these movements. When FOG is detected, the assistant provides a rhythmic auditory signal that stimulates the patient to resume walking. Ten PD patients tested the system while performing several walking tasks in the laboratory. More than 8 h of data were recorded. Eight patients experienced FOG during the study, and 237 FOG events were identified by professional physiotherapists in a post hoc video analysis. Our wearable assistant was able to provide online assistive feedback for PD patients when they experienced FOG. The system detected FOG events online with a sensitivity of 73.1% and a specificity of 81.6%. The majority of patients indicated that the context-aware automatic cueing was beneficial to them. Finally, we characterize the system performance with respect to the walking style, the sensor placement, and the dominant algorithm parameters.
Parkinson's disease (PD) is a neurodegenerative disorder resulting in motor disturbances that can impact normal gait. Although PD initially responds well to pharmacological treatment, as the disease progresses efficacy often fluctuates over the course of the day, and clinical management would benefit from long-term objective measures of gait. We have previously described a small device worn on the shank that uses acceleration and angular velocity sensors to calculate stride length and identify freezing of gait in PD patients. In this study we extend validation of the gait monitor to 24-h using simultaneous video observation of PD patients.
A sleep laboratory was adapted to perform 24-hr video monitoring of patients while wearing the device. Continuous video monitoring of a sleep lab, hallway, kitchen and conference room was performed using a 4-camera security system and recorded to hard disk. Subjects (3) wore the gait monitor on the left shank (just above the ankle) for a 24-h period beginning around 5 pm in the evening. Accuracy of stride length measures were assessed at the beginning and end of the 24-h epoch. Two independent observers rated the video logs to identify when subjects were walking or lying down.
The mean error in stride length at the start of recording was 0.05 m (SD 0) and at the conclusion of the 24 h epoch was 0.06 m (SD 0.026). There was full agreement between observer coding of the video logs and the output from the gait monitor software; that is, for every video observation of the subject walking there was a corresponding pulse in the monitor data that indicated gait.
The accuracy of ambulatory stride length measurement was maintained over the 24-h period, and there was 100% agreement between the autonomous detection of locomotion by the gait monitor and video observation.
The Timed Up and Go (TUG) test has been used to assess balance and mobility in Parkinson's Disease (PD). However, it is not known if this test is sensitive to subtle abnormalities present in early stages of the disease, when balance and gait problems are not clinically evident but may be detected with instrumented analysis of movement. We hypothesise that postural transitions and arm swing during gait will be the most sensitive characteristics of the TUG for early PD. In the present study, we instrumented the TUG test (iTUG) using portable inertial sensors, and extended the walking distance from 3 m (traditional TUG) to 7 m. Twelve subjects with early-to-moderate, untreated PD and 12 healthy individuals participated. Our findings show that although the stopwatch measure of TUG duration did not detect any abnormalities in early-to-mid-stage PD, the peak arm swing velocity on the more affected side, average turning velocity, cadence and peak trunk rotation velocity were significantly slower. These iTUG parameters were also correlated with the Unified Parkinson's Disease Rating Motor Scale. Thus, the iTUG test is sensitive to untreated PD and could potentially detect progression of PD and response to symptomatic and disease-modifying treatments.
Freezing in Parkinson's disease is a severe and disabling problem of unknown aetiology. The aim of this study was to analyse the temporal pattern and the magnitude of the electromyographic activity of the lower limb muscles just before freezing and to compare this with a voluntary stop and ongoing gait. We recruited 11 patients with a mean age of 64.8 years (SD 5.1) and a mean Unified Parkinson Disease Rating Scale (part III--off) score of 29 (SD 7.9). Within a standard 3D gait laboratory setting, surface electromyographic (EMG) data of the tibialis anterior (TA) and gastrocnemius (GS) muscles were collected using a portable EMG module. Patients in the off-phase of the medication cycle performed several trials of normal walking and voluntary stops or were exposed to freezing-provoking circumstances. Filtered EMG signals were rectified, smoothed and expressed as a percentage of the gait cycle. EMG onset was determined using a preset threshold, corrected after visual inspection. The magnitude of EMG was calculated by integrating EMG signals (iEMG) over (real) time. To control for the altered timing of activity, iEMG was also normalized for time (iEMGnormt). Analysis of variance of repeated measures analysis showed that significantly abnormal timing occurred in the TA and GS muscles with overall preserved reciprocity. Before freezing, TA swing activity already started prematurely during the pre-swing phase, whereas it was significantly shortened during the actual swing phase. For the GS muscle, a similar pattern of premature activation and termination was found during the stance phase before a freeze. GS activity also showed prolonged bursts of activity during the swing phase, not present during the normal and stop condition. Total iEMG activity of both TA and GS was significantly reduced during the pre-freezing gait cycles. However, when controlling for the altered duration of the bursts, the average iEMGnormt increased, as did the peak EMG in TA. In GS, iEMGnormt was not different in the three conditions. In conclusion, our data show that a consistent pattern of premature timing of TA and GS activity occurred before freezing, which was interpreted as a disturbance of central gait cycle timing. The total amount of EMG activity was reduced in both lower limb muscles due to the shortened time in which the muscles were active. In contrast to GS, activity in TA showed increased amplitudes of the EMG bursts, indicating a compensation strategy of pulling the leg into swing. The observed changes contribute to insufficient forward progression, deceleration and eventually a breakdown of movement.
Freezing of gait (FOG) is a common and debilitating, but largely mysterious, symptom of Parkinson's disease. In this review, we will discuss the cerebral substrate of FOG focusing on brain physiology and animal models. Walking is a combination of automatic movement processes, afferent information processing and intentional adjustments. Thus, normal gait requires a delicate balance between various interacting neuronal systems. To further understand gait control and specifically FOG, we will discuss the basic physiology of gait, animal models of gait disturbance including FOG, alternative etiologies of FOG and functional magnetic resonance studies investigating FOG. The outcome of these studies point to a dynamic network of cortical areas such as the supplementary motor area, as well as subcortical areas such as the striatum and the mesencephalic locomotor region (MLR) including the pedunculopontine nucleus (PPN). Additionally, we will review PPN (area) stimulation as a possible treatment for FOG, and ponder whether PPN stimulation truly is the right step forward. This article is protected by copyright. All rights reserved.
Background:
Despite the strong relationship between freezing of gait (FOG) and turning in Parkinson's disease (PD), few studies have addressed specific postural characteristics during turning that might contribute to freezing.
Methods:
Thirty participants with PD (16 freezers, 14 non-freezers) (all tested OFF medication) and 14 healthy controls walked 5 meters and turned 180° in a 3D gait laboratory. COM behavior was analyzed during four turning quadrants of 40° between 10° and 170° pelvic rotation and during 40° before actual FOG episodes. These pre-FOG segments were compared with similar turning sections in turns of freezers without FOG. Outcome parameters were turn time, COM distance, COM velocity, step width and the medial- and anterior COM position.
Results:
Turn time was increased in freezers compared to non-freezers (p=.000). No differences were found regarding COM distance and velocity during turning quadrants between groups and between freezers' pre-FOG segments and similar turning segments without FOG. Medial COM deviation was reduced in PD patients compared to controls (p=.004), but no differences were found between freezers and non-freezers. In turns with freezing, turn time increased (p=.005) and step width decreased (p=.025) pre-FOG. Freezers also showed a less medial (p=.020) and more anterior (p=.016) COM position pre-FOG compared to turning sections without FOG.
Conclusions:
Our results revealed no subgroup differences in COM behavior during uninterrupted turning. However, we found a reduced medial deviation, a forward COM shift and a decreased step width in freezers just before FOG episodes. These abnormalities may play a causal role, as they could hamper stability and fluent weight shifting necessary for continued stepping during turning.
Freezing of gait is a paroxysmal phenomenon that is frequently reported by the parkinsonian patients or their entourage. The phenomenon significantly alters quality of life but is often difficult to characterize in the physician's office. In the present review, we focus on the clinical characterization and quantification of freezing of gait. Various biomechanical methods (based mainly on time-frequency analysis) can be used to determine time-domain characteristics of freezing of gait. Methods already used to study non-gait freezing of other effectors (the lower limbs, upper limbs and orofacial area) are also being developed for the analysis of freezing in functional magnetic resonance imaging protocols. Here, we review the reliability of these methods and compare them with reliability of information obtained from physical examination and detailed analysis of the patient's medical history.
Importance
Freezing of gait (FOG) is a common axial symptom of Parkinson disease (PD).Objective
To determine the prevalence of FOG in a large group of PD patients, assess its relationship with quality of life and clinical and pharmacological factors, and explore its changes from the off to on conditions in patients with motor fluctuations.Design, Setting, and Participants
Cross-sectional survey of 683 patients with idiopathic PD. Scores for FOG were missing in 11 patients who were not included in the analysis. Patients were recruited from referral centers and general neurology clinics in public or private institutions in France.Exposure
Patients with FOG were identified as those with a score of 1 or greater on item 14 of the Unified Parkinson’s Disease Rating Scale (UPDRS) in the on condition. Item 14 scores for FOG in the off condition were also collected in patients with fluctuating motor symptoms.Main Outcomes and Measures
Quality of life (measured by the 39-item Parkinson’s Disease Questionnaire and 36-Item Short Form Health Survey), anxiety and depression (Hospital Anxiety and Depression Scale), clinical features (UPDRS), and drug consumption.Results
Of 672 PD patients, 257 reported FOG during the onstate (38.2%), which was significantly related to lower quality of life scores (P < .01). Freezing of gait was also correlated with longer PD duration (odds ratio, 1.92 [95% CI, 1.28-2.86]), higher UPDRS parts II and III scores (4.67 [3.21-6.78]), the presence of apathy (UPDRS item 4) (1.94 [1.33-2.82]), a higher levodopa equivalent daily dose (1.63 [1.09-2.43]), and more frequent exposure to antimuscarinics (3.07 [1.35-6.97]) (logistic regression). The FOG score improved from the off to on states in 148 of 174 patients with motor fluctuations (85.1%) and showed no change in 13.8%. The FOG score improved by more than 50% in 43.7% of patients. Greater improvement in the on state was observed in younger patients (r = −0.25; P < .01) with lower UPDRS II and III scores (r = −0.50; P < .01) and no antimuscarinic use (r = −0.21; P < .01).Conclusions and Relevance
Freezing of gait in PD patients correlates with poor quality of life, disease severity, apathy, and exposure to antimuscarinics. Dopaminergic therapy improved FOG in most patients with motor fluctuations, especially younger ones with less severe disease and no antimuscarinic use. This finding suggests that quality of life is impaired in PD patients with FOG and that optimizing dopaminergic therapy and avoiding antimuscarinics should be considered.
Objective
Impaired gait initiation (GI) in patients with advanced Parkinson’s disease (PD) is a typical functional sign of akinesia. Failure to initiate the first step is frequently presented by patients with freezing of gait (FOG) and is often considered as a subtype of freezing. The literature on the effects of cueing of GI preparation and execution remains controversial. Our objective was to establish whether auditory cueing improves the preparation and/or execution of GI in PD patients with a history of FOG.
Methods
We recorded first-step preparation and execution in 30 PD patients with confirmed FOG under two randomized conditions: self-triggered gait and gait cued by a sound beep in off and on-dopa conditions. Anticipatory postural adjustments (APAs) were evaluated by monitoring the trajectory of the centre of pressure.
Results
We compared the patients with 30 patients without history of FOG and 30 healthy controls (HCs). L-dopa only slightly improved characteristics of APAs in freezers but was effective to improve gait hypokinesia. Auditory cueing was effective in improving step preparation in freezers, who showed adequate APAs more frequently. As seen with HCs and patients without FOG, patients released their APAs quicker when auditory cueing was applied. However, cueing did not have a significant effect on step length. Clinically, auditory cueing also improved start hesitation in freezers.
Conclusions
Auditory cueing improved step preparation but not step execution in PD patients.
Significance
A failure to link step preparation and execution during GI may explain the poor first step execution seen in PD freezers.